func_env.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010, Digium, Inc.
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*! \file
 *
 * \brief Environment related dialplan functions
 *
 * \ingroup functions
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include <sys/stat.h>   /* stat(2) */
#include <libgen.h>     /* dirname and basename */
 
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/utils.h"
#include "asterisk/app.h"
#include "asterisk/file.h"
 
/*** DOCUMENTATION
    <function name="ENV" language="en_US">
        <since>
            <version>1.2.0</version>
        </since>
        <synopsis>
            Gets or sets the environment variable specified.
        </synopsis>
        <syntax>
            <parameter name="varname" required="true">
                <para>Environment variable name</para>
            </parameter>
        </syntax>
        <description>
            <para>Variables starting with <literal>AST_</literal> are reserved to the system and may not be set.</para>
            <para>Additionally, the following system variables are available as special built-in dialplan variables.
            These variables cannot be set or modified and are read-only.</para>
            <variablelist>
                <variable name="EPOCH">
                    <para>Current unix style epoch</para>
                </variable>
                <variable name="SYSTEMNAME">
                    <para>value of the <literal>systemname</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTCACHEDIR">
                    <para>value of the <literal>astcachedir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTETCDIR">
                    <para>value of the <literal>astetcdir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTMODDIR">
                    <para>value of the <literal>astmoddir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTVARLIBDIR">
                    <para>value of the <literal>astvarlib</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTDBDIR">
                    <para>value of the <literal>astdbdir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTKEYDIR">
                    <para>value of the <literal>astkeydir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTDATADIR">
                    <para>value of the <literal>astdatadir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTAGIDIR">
                    <para>value of the <literal>astagidir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTSPOOLDIR">
                    <para>value of the <literal>astspooldir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTRUNDIR">
                    <para>value of the <literal>astrundir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTLOGDIR">
                    <para>value of the <literal>astlogdir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ASTSBINDIR">
                    <para>value of the <literal>astsbindir</literal> option from <literal>asterisk.conf</literal></para>
                </variable>
                <variable name="ENTITYID">
                    <para>Global Entity ID set automatically, or from <literal>asterisk.conf</literal></para>
                </variable>
            </variablelist>
        </description>
    </function>
    <function name="STAT" language="en_US">
        <since>
            <version>1.4.0</version>
        </since>
        <synopsis>
            Does a check on the specified file.
        </synopsis>
        <syntax>
            <parameter name="flag" required="true">
                <para>Flag may be one of the following:</para>
                <para>d - Checks if the file is a directory.</para>
                <para>e - Checks if the file exists.</para>
                <para>f - Checks if the file is a regular file.</para>
                <para>m - Returns the file mode (in octal)</para>
                <para>s - Returns the size (in bytes) of the file</para>
                <para>A - Returns the epoch at which the file was last accessed.</para>
                <para>C - Returns the epoch at which the inode was last changed.</para>
                <para>M - Returns the epoch at which the file was last modified.</para>
            </parameter>
            <parameter name="filename" required="true" />
        </syntax>
        <description>
            <note>
                <para>If <literal>live_dangerously</literal> in <literal>asterisk.conf</literal>
                is set to <literal>no</literal>, this function can only be executed from the
                dialplan, and not directly from external protocols.</para>
            </note>
        </description>
    </function>
    <function name="FILE" language="en_US">
        <since>
            <version>1.6.0</version>
        </since>
        <synopsis>
            Read or write text file.
        </synopsis>
        <syntax>
            <parameter name="filename" required="true" />
            <parameter name="offset">
                <para>Maybe specified as any number. If negative, <replaceable>offset</replaceable> specifies the number
                of bytes back from the end of the file.</para>
            </parameter>
            <parameter name="length">
                <para>If specified, will limit the length of the data read to that size. If negative,
                trims <replaceable>length</replaceable> bytes from the end of the file.</para>
            </parameter>
            <parameter name="options">
                <optionlist>
                    <option name="l">
                        <para>Line mode:  offset and length are assumed to be
                        measured in lines, instead of byte offsets.</para>
                    </option>
                    <option name="a">
                        <para>In write mode only, the append option is used to
                        append to the end of the file, instead of overwriting
                        the existing file.</para>
                    </option>
                    <option name="d">
                        <para>In write mode and line mode only, this option does
                        not automatically append a newline string to the end of
                        a value.  This is useful for deleting lines, instead of
                        setting them to blank.</para>
                    </option>
                </optionlist>
            </parameter>
            <parameter name="format">
                <para>The <replaceable>format</replaceable> parameter may be
                used to delimit the type of line terminators in line mode.</para>
                <optionlist>
                    <option name="u">
                        <para>Unix newline format.</para>
                    </option>
                    <option name="d">
                        <para>DOS newline format.</para>
                    </option>
                    <option name="m">
                        <para>Macintosh newline format.</para>
                    </option>
                </optionlist>
            </parameter>
        </syntax>
        <description>
            <para>Read and write text file in character and line mode.</para>
            <para>Examples:</para>
            <para>Read mode (byte):</para>
            <example title="Reads the entire content of the file">
            same => n,Set(foo=${FILE(/tmp/test.txt)})
            </example>
            <example title="Reads from the 11th byte to the end of the file (i.e. skips the first 10)">
            same => n,Set(foo=${FILE(/tmp/test.txt,10)})
            </example>
            <example title="Reads from the 11th to 20th byte in the file (i.e. skip the first 10, then read 10 bytes)">
            same => n,Set(foo=${FILE(/tmp/test.txt,10,10)})
            </example>
            <para>Read mode (line):</para>
            <example title="Reads the 3rd line of the file">
            same => n,Set(foo=${FILE(/tmp/test.txt,3,1,l)})
            </example>
            <example title="Reads the 3rd and 4th lines of the file">
            same => n,Set(foo=${FILE(/tmp/test.txt,3,2,l)})
            </example>
            <example title="Reads from the third line to the end of the file">
            same => n,Set(foo=${FILE(/tmp/test.txt,3,,l)})
            </example>
            <example title="Reads the last three lines of the file">
            same => n,Set(foo=${FILE(/tmp/test.txt,-3,,l)})
            </example>
            <example title="Reads the 3rd line of a DOS-formatted file">
            same => n,Set(foo=${FILE(/tmp/test.txt,3,1,l,d)})
            </example>
            <para>Write mode (byte):</para>
            <example title="Truncate the file and write bar">
            same => n,Set(FILE(/tmp/test.txt)=bar)
            </example>
            <example title="Append bar">
            same => n,Set(FILE(/tmp/test.txt,,,a)=bar)
            </example>
            <example title="Replace the first byte with bar (replaces 1 character with 3)">
            same => n,Set(FILE(/tmp/test.txt,0,1)=bar)
            </example>
            <example title="Replace 10 bytes beginning at the 21st byte of the file with bar">
            same => n,Set(FILE(/tmp/test.txt,20,10)=bar)
            </example>
            <example title="Replace all bytes from the 21st with bar">
            same => n,Set(FILE(/tmp/test.txt,20)=bar)
            </example>
            <example title="Insert bar after the 4th character">
            same => n,Set(FILE(/tmp/test.txt,4,0)=bar)
            </example>
            <para>Write mode (line):</para>
            <example title="Replace the first line of the file with bar">
            same => n,Set(FILE(/tmp/foo.txt,0,1,l)=bar)
            </example>
            <example title="Replace the last line of the file with bar">
            same => n,Set(FILE(/tmp/foo.txt,-1,,l)=bar)
            </example>
            <example title="Append bar to the file with a newline">
            same => n,Set(FILE(/tmp/foo.txt,,,al)=bar)
            </example>
            <note>
                <para>If <literal>live_dangerously</literal> in <literal>asterisk.conf</literal>
                is set to <literal>no</literal>, this function can only be executed from the
                dialplan, and not directly from external protocols.</para>
            </note>
        </description>
        <see-also>
            <ref type="function">FILE_COUNT_LINE</ref>
            <ref type="function">FILE_FORMAT</ref>
        </see-also>
    </function>
    <function name="FILE_COUNT_LINE" language="en_US">
        <since>
            <version>1.8.0</version>
        </since>
        <synopsis>
            Obtains the number of lines of a text file.
        </synopsis>
        <syntax>
            <parameter name="filename" required="true" />
            <parameter name="format">
                <para>Format may be one of the following:</para>
                <optionlist>
                    <option name="u">
                        <para>Unix newline format.</para>
                    </option>
                    <option name="d">
                        <para>DOS newline format.</para>
                    </option>
                    <option name="m">
                        <para>Macintosh newline format.</para>
                    </option>
                </optionlist>
                <note><para>If not specified, an attempt will be made to determine the newline format type.</para></note>
            </parameter>
        </syntax>
        <description>
            <para>Returns the number of lines, or <literal>-1</literal> on error.</para>
            <note>
                <para>If <literal>live_dangerously</literal> in <literal>asterisk.conf</literal>
                is set to <literal>no</literal>, this function can only be executed from the
                dialplan, and not directly from external protocols.</para>
            </note>
        </description>
        <see-also>
            <ref type="function">FILE</ref>
            <ref type="function">FILE_FORMAT</ref>
        </see-also>
    </function>
    <function name="FILE_FORMAT" language="en_US">
        <since>
            <version>1.8.0</version>
        </since>
        <synopsis>
            Return the newline format of a text file.
        </synopsis>
        <syntax>
            <parameter name="filename" required="true" />
        </syntax>
        <description>
            <para>Return the line terminator type:</para>
            <para>'u' - Unix "\n" format</para>
            <para>'d' - DOS "\r\n" format</para>
            <para>'m' - Macintosh "\r" format</para>
            <para>'x' - Cannot be determined</para>
            <note>
                <para>If <literal>live_dangerously</literal> in <literal>asterisk.conf</literal>
                is set to <literal>no</literal>, this function can only be executed from the
                dialplan, and not directly from external protocols.</para>
            </note>
        </description>
        <see-also>
            <ref type="function">FILE</ref>
            <ref type="function">FILE_COUNT_LINE</ref>
        </see-also>
    </function>
    <function name="BASENAME" language="en_US">
        <since>
            <version>16.21.0</version>
            <version>18.7.0</version>
        </since>
        <synopsis>
            Return the name of a file.
        </synopsis>
        <syntax>
            <parameter name="filename" required="true" />
        </syntax>
        <description>
            <para>Return the base file name, given a full file path.</para>
            <example title="Directory name">
            same => n,Set(basename=${BASENAME(/etc/asterisk/extensions.conf)})
            same => n,NoOp(${basename}) ; outputs extensions.conf
            </example>
        </description>
        <see-also>
            <ref type="function">DIRNAME</ref>
        </see-also>
    </function>
    <function name="DIRNAME" language="en_US">
        <since>
            <version>16.21.0</version>
            <version>18.7.0</version>
        </since>
        <synopsis>
            Return the directory of a file.
        </synopsis>
        <syntax>
            <parameter name="filename" required="true" />
        </syntax>
        <description>
            <para>Return the directory of a file, given a full file path.</para>
            <example title="Directory name">
            same => n,Set(dirname=${DIRNAME(/etc/asterisk/extensions.conf)})
            same => n,NoOp(${dirname}) ; outputs /etc/asterisk
            </example>
        </description>
        <see-also>
            <ref type="function">BASENAME</ref>
        </see-also>
    </function>
 ***/
 
static int env_read(struct ast_channel *chan, const char *cmd, char *data,
            char *buf, size_t len)
{
    char *ret = NULL;
 
    *buf = '\0';
 
    if (data)
        ret = getenv(data);
 
    if (ret)
        ast_copy_string(buf, ret, len);
 
    return 0;
}
 
static int env_write(struct ast_channel *chan, const char *cmd, char *data,
             const char *value)
{
    if (!ast_strlen_zero(data) && strncmp(data, "AST_", 4)) {
        if (!ast_strlen_zero(value)) {
            setenv(data, value, 1);
        } else {
            unsetenv(data);
        }
    }
 
    return 0;
}
 
static int stat_read(struct ast_channel *chan, const char *cmd, char *data,
             char *buf, size_t len)
{
    char *action;
    struct stat s;
 
    ast_copy_string(buf, "0", len);
 
    action = strsep(&data, ",");
    if (stat(data, &s)) {
        return 0;
    } else {
        switch (*action) {
        case 'e':
            strcpy(buf, "1");
            break;
        case 's':
            snprintf(buf, len, "%u", (unsigned int) s.st_size);
            break;
        case 'f':
            snprintf(buf, len, "%d", S_ISREG(s.st_mode) ? 1 : 0);
            break;
        case 'd':
            snprintf(buf, len, "%d", S_ISDIR(s.st_mode) ? 1 : 0);
            break;
        case 'M':
            snprintf(buf, len, "%d", (int) s.st_mtime);
            break;
        case 'A':
            snprintf(buf, len, "%d", (int) s.st_mtime);
            break;
        case 'C':
            snprintf(buf, len, "%d", (int) s.st_ctime);
            break;
        case 'm':
            snprintf(buf, len, "%o", (unsigned int) s.st_mode);
            break;
        }
    }
 
    return 0;
}
 
enum file_format {
    FF_UNKNOWN = -1,
    FF_UNIX,
    FF_DOS,
    FF_MAC,
};
 
static int64_t count_lines(const char *filename, enum file_format newline_format)
{
    int count = 0;
    char fbuf[4096];
    FILE *ff;
 
    if (!(ff = fopen(filename, "r"))) {
        ast_log(LOG_ERROR, "Unable to open '%s': %s\n", filename, strerror(errno));
        return -1;
    }
 
    while (fgets(fbuf, sizeof(fbuf), ff)) {
        char *next = fbuf, *first_cr = NULL, *first_nl = NULL;
 
        /* Must do it this way, because if the fileformat is FF_MAC, then Unix
         * assumptions about line-format will not come into play. */
        while (next) {
            if (newline_format == FF_DOS || newline_format == FF_MAC || newline_format == FF_UNKNOWN) {
                first_cr = strchr(next, '\r');
            }
            if (newline_format == FF_UNIX || newline_format == FF_UNKNOWN) {
                first_nl = strchr(next, '\n');
            }
 
            /* No terminators found in buffer */
            if (!first_cr && !first_nl) {
                break;
            }
 
            if (newline_format == FF_UNKNOWN) {
                if ((first_cr && !first_nl) || (first_cr && first_cr < first_nl)) {
                    if (first_nl && first_nl == first_cr + 1) {
                        newline_format = FF_DOS;
                    } else if (first_cr && first_cr == &fbuf[sizeof(fbuf) - 2]) {
                        /* Get it on the next pass */
                        fseek(ff, -1, SEEK_CUR);
                        break;
                    } else {
                        newline_format = FF_MAC;
                        first_nl = NULL;
                    }
                } else {
                    newline_format = FF_UNIX;
                    first_cr = NULL;
                }
                /* Jump down into next section */
            }
 
            if (newline_format == FF_DOS) {
                if (first_nl && first_cr && first_nl == first_cr + 1) {
                    next = first_nl + 1;
                    count++;
                } else if (first_cr == &fbuf[sizeof(fbuf) - 2]) {
                    /* Get it on the next pass */
                    fseek(ff, -1, SEEK_CUR);
                    break;
                }
            } else if (newline_format == FF_MAC) {
                if (first_cr) {
                    next = first_cr + 1;
                    count++;
                }
            } else if (newline_format == FF_UNIX) {
                if (first_nl) {
                    next = first_nl + 1;
                    count++;
                }
            }
        }
    }
    fclose(ff);
 
    return count;
}
 
static int file_count_line(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **buf, ssize_t len)
{
    enum file_format newline_format = FF_UNKNOWN;
    int64_t count;
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(filename);
        AST_APP_ARG(format);
    );
 
    AST_STANDARD_APP_ARGS(args, data);
    if (args.argc > 1) {
        if (tolower(args.format[0]) == 'd') {
            newline_format = FF_DOS;
        } else if (tolower(args.format[0]) == 'm') {
            newline_format = FF_MAC;
        } else if (tolower(args.format[0]) == 'u') {
            newline_format = FF_UNIX;
        }
    }
 
    count = count_lines(args.filename, newline_format);
    ast_str_set(buf, len, "%" PRId64, count);
    return 0;
}
 
#define LINE_COUNTER(cptr, term, counter) \
    if (*cptr == '\n' && term == FF_UNIX) { \
        counter++; \
    } else if (*cptr == '\n' && term == FF_DOS && dos_state == 0) { \
        dos_state = 1; \
    } else if (*cptr == '\r' && term == FF_DOS && dos_state == 1) { \
        dos_state = 0; \
        counter++; \
    } else if (*cptr == '\r' && term == FF_MAC) { \
        counter++; \
    } else if (term == FF_DOS) { \
        dos_state = 0; \
    }
 
static enum file_format file2format(const char *filename)
{
    FILE *ff;
    char fbuf[4096];
    char *first_cr, *first_nl;
    enum file_format newline_format = FF_UNKNOWN;
 
    if (!(ff = fopen(filename, "r"))) {
        ast_log(LOG_ERROR, "Cannot open '%s': %s\n", filename, strerror(errno));
        return -1;
    }
 
    while (fgets(fbuf, sizeof(fbuf), ff)) {
        first_cr = strchr(fbuf, '\r');
        first_nl = strchr(fbuf, '\n');
 
        if (!first_cr && !first_nl) {
            continue;
        }
 
        if ((first_cr && !first_nl) || (first_cr && first_cr < first_nl)) {
 
            if (first_nl && first_nl == first_cr + 1) {
                newline_format = FF_DOS;
            } else if (first_cr && first_cr == &fbuf[sizeof(fbuf) - 2]) {
                /* Edge case: get it on the next pass */
                fseek(ff, -1, SEEK_CUR);
                continue;
            } else {
                newline_format = FF_MAC;
            }
        } else {
            newline_format = FF_UNIX;
        }
        break;
    }
    fclose(ff);
    return newline_format;
}
 
static int file_format(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **buf, ssize_t len)
{
    enum file_format newline_format = file2format(data);
    ast_str_set(buf, len, "%c", newline_format == FF_UNIX ? 'u' : newline_format == FF_DOS ? 'd' : newline_format == FF_MAC ? 'm' : 'x');
    return 0;
}
 
static int file_dirname(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
    char *ret = NULL;
 
    *buf = '\0';
 
    if (data) {
        ret = dirname(data);
    }
 
    if (ret) {
        ast_copy_string(buf, ret, len);
    }
 
    return 0;
}
 
static int file_basename(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
    char *ret = NULL;
 
    *buf = '\0';
 
    if (data) {
        ret = basename(data);
    }
 
    if (ret) {
        ast_copy_string(buf, ret, len);
    }
 
    return 0;
}
 
static int file_read(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **buf, ssize_t len)
{
    FILE *ff;
    int64_t offset = 0, length = LLONG_MAX;
    enum file_format format = FF_UNKNOWN;
    char fbuf[4096];
    int64_t flength, i; /* iterator needs to be signed, so it can go negative and terminate the loop */
    int64_t offset_offset = -1, length_offset = -1;
    char dos_state = 0;
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(filename);
        AST_APP_ARG(offset);
        AST_APP_ARG(length);
        AST_APP_ARG(options);
        AST_APP_ARG(fileformat);
    );
 
    AST_STANDARD_APP_ARGS(args, data);
 
    if (args.argc > 1) {
        sscanf(args.offset, "%" SCNd64, &offset);
    }
    if (args.argc > 2) {
        sscanf(args.length, "%" SCNd64, &length);
    }
 
    if (args.argc < 4 || !strchr(args.options, 'l')) {
        /* Character-based mode */
        off_t off_i;
 
        if (!(ff = fopen(args.filename, "r"))) {
            ast_log(LOG_WARNING, "Cannot open file '%s' for reading: %s\n", args.filename, strerror(errno));
            return 0;
        }
 
        if (fseeko(ff, 0, SEEK_END) < 0) {
            ast_log(LOG_ERROR, "Cannot seek to end of '%s': %s\n", args.filename, strerror(errno));
            fclose(ff);
            return -1;
        }
        flength = ftello(ff);
 
        if (offset < 0) {
            fseeko(ff, offset, SEEK_END);
            if ((offset = ftello(ff)) < 0) {
                ast_log(AST_LOG_ERROR, "Cannot determine offset position of '%s': %s\n", args.filename, strerror(errno));
                fclose(ff);
                return -1;
            }
        }
        if (length < 0) {
            fseeko(ff, length, SEEK_END);
            if ((length = ftello(ff)) - offset < 0) {
                /* Eliminates all results */
                fclose(ff);
                return -1;
            }
        } else if (length == LLONG_MAX) {
            fseeko(ff, 0, SEEK_END);
            length = ftello(ff);
        }
 
        ast_str_reset(*buf);
 
        fseeko(ff, offset, SEEK_SET);
        for (off_i = ftello(ff); off_i < flength && off_i < offset + length; off_i += sizeof(fbuf)) {
            /* Calculate if we need to retrieve just a portion of the file in memory */
            size_t toappend = sizeof(fbuf);
 
            if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                ast_log(LOG_ERROR, "Short read?!!\n");
                break;
            }
 
            /* Don't go past the length requested */
            if (off_i + toappend > offset + length) {
                toappend = MIN(offset + length - off_i, flength - off_i);
            }
 
            ast_str_append_substr(buf, len, fbuf, toappend);
        }
        fclose(ff);
        return 0;
    }
 
    /* Line-based read */
    if (args.argc == 5) {
        if (tolower(args.fileformat[0]) == 'd') {
            format = FF_DOS;
        } else if (tolower(args.fileformat[0]) == 'm') {
            format = FF_MAC;
        } else if (tolower(args.fileformat[0]) == 'u') {
            format = FF_UNIX;
        }
    }
 
    if (format == FF_UNKNOWN) {
        if ((format = file2format(args.filename)) == FF_UNKNOWN) {
            ast_log(LOG_WARNING, "'%s' is not a line-based file\n", args.filename);
            return -1;
        }
    }
 
    if (offset < 0 && length <= offset) {
        /* Length eliminates all content */
        return -1;
    } else if (offset == 0) {
        offset_offset = 0;
    }
 
    if (!(ff = fopen(args.filename, "r"))) {
        ast_log(LOG_ERROR, "Cannot open '%s': %s\n", args.filename, strerror(errno));
        return -1;
    }
 
    if (fseek(ff, 0, SEEK_END)) {
        ast_log(LOG_ERROR, "Cannot seek to end of file '%s': %s\n", args.filename, strerror(errno));
        fclose(ff);
        return -1;
    }
 
    flength = ftello(ff);
 
    if (length == LLONG_MAX) {
        length_offset = flength;
    }
 
    /* For negative offset and/or negative length */
    if (offset < 0 || length < 0) {
        int64_t count = 0;
        /* Start with an even multiple of fbuf, so at the end of reading with a
         * 0 offset, we don't try to go past the beginning of the file. */
        for (i = (flength / sizeof(fbuf)) * sizeof(fbuf); i >= 0; i -= sizeof(fbuf)) {
            size_t end;
            char *pos;
            if (fseeko(ff, i, SEEK_SET)) {
                ast_log(LOG_ERROR, "Cannot seek to offset %" PRId64 ": %s\n", i, strerror(errno));
            }
            end = fread(fbuf, 1, sizeof(fbuf), ff);
            for (pos = (end < sizeof(fbuf) ? fbuf + end - 1 : fbuf + sizeof(fbuf) - 1); pos >= fbuf; pos--) {
                LINE_COUNTER(pos, format, count);
 
                if (length < 0 && count * -1 == length) {
                    length_offset = i + (pos - fbuf);
                } else if (offset < 0 && count * -1 == (offset - 1)) {
                    /* Found our initial offset.  We're done with reverse motion! */
                    if (format == FF_DOS) {
                        offset_offset = i + (pos - fbuf) + 2;
                    } else {
                        offset_offset = i + (pos - fbuf) + 1;
                    }
                    break;
                }
            }
            if ((offset < 0 && offset_offset >= 0) || (offset >= 0 && length_offset >= 0)) {
                break;
            }
        }
        /* We're at the beginning, and the negative offset indicates the exact number of lines in the file */
        if (offset < 0 && offset_offset < 0 && offset == count * -1) {
            offset_offset = 0;
        }
    }
 
    /* Positve line offset */
    if (offset > 0) {
        int64_t count = 0;
        fseek(ff, 0, SEEK_SET);
        for (i = 0; i < flength; i += sizeof(fbuf)) {
            char *pos;
            if (i + sizeof(fbuf) <= flength) {
                /* Don't let previous values influence current counts, due to short reads */
                memset(fbuf, 0, sizeof(fbuf));
            }
            if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                ast_log(LOG_ERROR, "Short read?!!\n");
                fclose(ff);
                return -1;
            }
            for (pos = fbuf; pos < fbuf + sizeof(fbuf); pos++) {
                LINE_COUNTER(pos, format, count);
 
                if (count == offset) {
                    offset_offset = i + (pos - fbuf) + 1;
                    break;
                }
            }
            if (offset_offset >= 0) {
                break;
            }
        }
    }
 
    if (offset_offset < 0) {
        ast_log(LOG_ERROR, "Offset '%s' refers to before the beginning of the file!\n", args.offset);
        fclose(ff);
        return -1;
    }
 
    ast_str_reset(*buf);
    if (fseeko(ff, offset_offset, SEEK_SET)) {
        ast_log(LOG_ERROR, "fseeko failed: %s\n", strerror(errno));
    }
 
    /* If we have both offset_offset and length_offset, then grabbing the
     * buffer is simply a matter of just retrieving the file and adding it
     * to buf.  Otherwise, we need to run byte-by-byte forward until the
     * length is complete. */
    if (length_offset >= 0) {
        ast_debug(3, "offset=%" PRId64 ", length=%" PRId64 ", offset_offset=%" PRId64 ", length_offset=%" PRId64 "\n", offset, length, offset_offset, length_offset);
        for (i = offset_offset; i < length_offset; i += sizeof(fbuf)) {
            if (fread(fbuf, 1, i + sizeof(fbuf) > flength ? flength - i : sizeof(fbuf), ff) < (i + sizeof(fbuf) > flength ? flength - i : sizeof(fbuf))) {
                ast_log(LOG_ERROR, "Short read?!!\n");
            }
            ast_debug(3, "Appending first %" PRId64" bytes of fbuf=%s\n", (int64_t)(i + sizeof(fbuf) > length_offset ? length_offset - i : sizeof(fbuf)), fbuf);
            ast_str_append_substr(buf, len, fbuf, i + sizeof(fbuf) > length_offset ? length_offset - i : sizeof(fbuf));
        }
    } else if (length == 0) {
        /* Nothing to do */
    } else {
        /* Positive line offset */
        int64_t current_length = 0;
        char dos_state = 0;
        ast_debug(3, "offset=%" PRId64 ", length=%" PRId64 ", offset_offset=%" PRId64 ", length_offset=%" PRId64 "\n", offset, length, offset_offset, length_offset);
        for (i = offset_offset; i < flength; i += sizeof(fbuf)) {
            char *pos;
            size_t bytes_read;
            if ((bytes_read = fread(fbuf, 1, sizeof(fbuf), ff)) < sizeof(fbuf) && !feof(ff)) {
                ast_log(LOG_ERROR, "Short read?!!\n");
                fclose(ff);
                return -1;
            }
            for (pos = fbuf; pos < fbuf + bytes_read; pos++) {
                LINE_COUNTER(pos, format, current_length);
 
                if (current_length == length) {
                    length_offset = i + (pos - fbuf) + 1;
                    break;
                }
            }
            ast_debug(3, "length_offset=%" PRId64 ", length_offset - i=%" PRId64 "\n", length_offset, length_offset - i);
            ast_str_append_substr(buf, len, fbuf, (length_offset >= 0) ? length_offset - i : (flength > i + sizeof(fbuf)) ? sizeof(fbuf) : flength - i);
 
            if (length_offset >= 0) {
                break;
            }
        }
    }
 
    fclose(ff);
    return 0;
}
 
const char *format2term(enum file_format f) __attribute__((const));
const char *format2term(enum file_format f)
{
    const char *term[] = { "", "\n", "\r\n", "\r" };
    return term[f + 1];
}
 
static int file_write(struct ast_channel *chan, const char *cmd, char *data, const char *value)
{
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(filename);
        AST_APP_ARG(offset);
        AST_APP_ARG(length);
        AST_APP_ARG(options);
        AST_APP_ARG(format);
    );
    int64_t offset = 0, length = LLONG_MAX;
    off_t flength, vlength;
    size_t foplen = 0;
    FILE *ff;
 
    AST_STANDARD_APP_ARGS(args, data);
 
    if (args.argc > 1) {
        sscanf(args.offset, "%" SCNd64, &offset);
    }
    if (args.argc > 2) {
        sscanf(args.length, "%" SCNd64, &length);
    }
 
    vlength = strlen(value);
 
    if (args.argc < 4 || !strchr(args.options, 'l')) {
        /* Character-based mode */
 
        if (args.argc > 3 && strchr(args.options, 'a')) {
            /* Append mode */
            if (!(ff = fopen(args.filename, "a"))) {
                ast_log(LOG_WARNING, "Cannot open file '%s' for appending: %s\n", args.filename, strerror(errno));
                return 0;
            }
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            fclose(ff);
            return 0;
        } else if (offset == 0 && length == LLONG_MAX) {
            if (!(ff = fopen(args.filename, "w"))) {
                ast_log(LOG_WARNING, "Cannot open file '%s' for writing: %s\n", args.filename, strerror(errno));
                return 0;
            }
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            fclose(ff);
            return 0;
        }
 
        if (!(ff = fopen(args.filename, "r+"))) {
            ast_log(LOG_WARNING, "Cannot open file '%s' for modification: %s\n", args.filename, strerror(errno));
            return 0;
        }
        fseeko(ff, 0, SEEK_END);
        flength = ftello(ff);
 
        if (offset < 0) {
            if (fseeko(ff, offset, SEEK_END)) {
                ast_log(LOG_ERROR, "Cannot seek to offset of '%s': %s\n", args.filename, strerror(errno));
                fclose(ff);
                return -1;
            }
            if ((offset = ftello(ff)) < 0) {
                ast_log(AST_LOG_ERROR, "Cannot determine offset position of '%s': %s\n", args.filename, strerror(errno));
                fclose(ff);
                return -1;
            }
        }
 
        if (length < 0) {
            length = flength - offset + length;
            if (length < 0) {
                ast_log(LOG_ERROR, "Length '%s' exceeds the file length.  No data will be written.\n", args.length);
                fclose(ff);
                return -1;
            }
        }
 
        fseeko(ff, offset, SEEK_SET);
 
        ast_debug(3, "offset=%s/%" PRId64 ", length=%s/%" PRId64 ", vlength=%" PRId64 ", flength=%" PRId64 "\n",
            S_OR(args.offset, "(null)"), offset, S_OR(args.length, "(null)"), length, vlength, flength);
 
        if (length == vlength) {
            /* Simplest case, a straight replace */
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            fclose(ff);
        } else if (length == LLONG_MAX) {
            /* Simple truncation */
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            fclose(ff);
            if (truncate(args.filename, offset + vlength)) {
                ast_log(LOG_ERROR, "Unable to truncate the file: %s\n", strerror(errno));
            }
        } else if (length > vlength) {
            /* More complex -- need to close a gap */
            char fbuf[4096];
            off_t cur;
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            fseeko(ff, length - vlength, SEEK_CUR);
            while ((cur = ftello(ff)) < flength) {
                if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                    ast_log(LOG_ERROR, "Short read?!!\n");
                }
                fseeko(ff, cur + vlength - length, SEEK_SET);
                if (fwrite(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf)) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                }
                /* Seek to where we stopped reading */
                if (fseeko(ff, cur + sizeof(fbuf), SEEK_SET) < 0) {
                    /* Only reason for seek to fail is EOF */
                    break;
                }
            }
            fclose(ff);
            if (truncate(args.filename, flength - (length - vlength))) {
                ast_log(LOG_ERROR, "Unable to truncate the file: %s\n", strerror(errno));
            }
        } else {
            /* Most complex -- need to open a gap */
            char fbuf[4096];
            off_t lastwritten = flength + vlength - length;
 
            /* Start reading exactly the buffer size back from the end. */
            fseeko(ff, flength - sizeof(fbuf), SEEK_SET);
            while (offset < ftello(ff)) {
                if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf)) {
                    ast_log(LOG_ERROR, "Short read?!!\n");
                    fclose(ff);
                    return -1;
                }
                /* Since the read moved our file ptr forward, we reverse, but
                 * seek an offset equal to the amount we want to extend the
                 * file by */
                fseeko(ff, vlength - length - sizeof(fbuf), SEEK_CUR);
 
                /* Note the location of this buffer -- we must not overwrite this position. */
                lastwritten = ftello(ff);
 
                if (fwrite(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf)) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                    fclose(ff);
                    return -1;
                }
 
                if (lastwritten < offset + sizeof(fbuf)) {
                    break;
                }
                /* Our file pointer is now either pointing to the end of the
                 * file (new position) or a multiple of the fbuf size back from
                 * that point.  Move back to where we want to start reading
                 * again.  We never actually try to read beyond the end of the
                 * file, so we don't have do deal with short reads, as we would
                 * when we're shortening the file. */
                fseeko(ff, 2 * sizeof(fbuf) + vlength - length, SEEK_CUR);
            }
 
            /* Last part of the file that we need to preserve */
            if (fseeko(ff, offset + length, SEEK_SET)) {
                ast_log(LOG_WARNING, "Unable to seek to %" PRId64 " + %" PRId64 " != %" PRId64 "?)\n", offset, length, ftello(ff));
            }
 
            /* Doesn't matter how much we read -- just need to restrict the write */
            ast_debug(1, "Reading at %" PRId64 "\n", ftello(ff));
            if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                ast_log(LOG_ERROR, "Short read?!!\n");
            }
            fseek(ff, offset, SEEK_SET);
            /* Write out the value, then write just up until where we last moved some data */
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            } else {
                off_t curpos = ftello(ff);
                foplen = lastwritten - curpos;
                if (fwrite(fbuf, 1, foplen, ff) < foplen) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                }
            }
            fclose(ff);
        }
    } else {
        enum file_format newline_format = FF_UNKNOWN;
 
        /* Line mode */
        if (args.argc == 5) {
            if (tolower(args.format[0]) == 'u') {
                newline_format = FF_UNIX;
            } else if (tolower(args.format[0]) == 'm') {
                newline_format = FF_MAC;
            } else if (tolower(args.format[0]) == 'd') {
                newline_format = FF_DOS;
            }
        }
        if (newline_format == FF_UNKNOWN && (newline_format = file2format(args.filename)) == FF_UNKNOWN) {
            ast_log(LOG_ERROR, "File '%s' not in line format\n", args.filename);
            return -1;
        }
 
        if (strchr(args.options, 'a')) {
            /* Append to file */
            if (!(ff = fopen(args.filename, "a"))) {
                ast_log(LOG_ERROR, "Unable to open '%s' for appending: %s\n", args.filename, strerror(errno));
                return -1;
            }
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            } else if (!strchr(args.options, 'd') && fwrite(format2term(newline_format), 1, strlen(format2term(newline_format)), ff) < strlen(format2term(newline_format))) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            fclose(ff);
        } else if (offset == 0 && length == LLONG_MAX) {
            /* Overwrite file */
            off_t truncsize;
            if (!(ff = fopen(args.filename, "w"))) {
                ast_log(LOG_ERROR, "Unable to open '%s' for writing: %s\n", args.filename, strerror(errno));
                return -1;
            }
            if (fwrite(value, 1, vlength, ff) < vlength) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            } else if (!strchr(args.options, 'd') && fwrite(format2term(newline_format), 1, strlen(format2term(newline_format)), ff) < strlen(format2term(newline_format))) {
                ast_log(LOG_ERROR, "Short write?!!\n");
            }
            if ((truncsize = ftello(ff)) < 0) {
                ast_log(AST_LOG_ERROR, "Unable to determine truncate position of '%s': %s\n", args.filename, strerror(errno));
            }
            fclose(ff);
            if (truncsize >= 0 && truncate(args.filename, truncsize)) {
                ast_log(LOG_ERROR, "Unable to truncate file '%s': %s\n", args.filename, strerror(errno));
                return -1;
            }
        } else {
            int64_t offset_offset = (offset == 0 ? 0 : -1), length_offset = -1, flength, i, current_length = 0;
            char dos_state = 0, fbuf[4096];
 
            if (offset < 0 && length < offset) {
                /* Nonsense! */
                ast_log(LOG_ERROR, "Length cannot specify a position prior to the offset\n");
                return -1;
            }
 
            if (!(ff = fopen(args.filename, "r+"))) {
                ast_log(LOG_ERROR, "Cannot open '%s' for modification: %s\n", args.filename, strerror(errno));
                return -1;
            }
 
            if (fseek(ff, 0, SEEK_END)) {
                ast_log(LOG_ERROR, "Cannot seek to end of file '%s': %s\n", args.filename, strerror(errno));
                fclose(ff);
                return -1;
            }
            if ((flength = ftello(ff)) < 0) {
                ast_log(AST_LOG_ERROR, "Cannot determine end position of file '%s': %s\n", args.filename, strerror(errno));
                fclose(ff);
                return -1;
            }
 
            /* For negative offset and/or negative length */
            if (offset < 0 || length < 0) {
                int64_t count = 0;
                for (i = (flength / sizeof(fbuf)) * sizeof(fbuf); i >= 0; i -= sizeof(fbuf)) {
                    char *pos;
                    if (fseeko(ff, i, SEEK_SET)) {
                        ast_log(LOG_ERROR, "Cannot seek to offset %" PRId64 ": %s\n", i, strerror(errno));
                    }
                    if (i + sizeof(fbuf) >= flength) {
                        memset(fbuf, 0, sizeof(fbuf));
                    }
                    if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                        ast_log(LOG_ERROR, "Short read: %s\n", strerror(errno));
                        fclose(ff);
                        return -1;
                    }
                    for (pos = fbuf + sizeof(fbuf) - 1; pos >= fbuf; pos--) {
                        LINE_COUNTER(pos, newline_format, count);
 
                        if (length < 0 && count * -1 == length) {
                            length_offset = i + (pos - fbuf);
                        } else if (offset < 0 && count * -1 == (offset - 1)) {
                            /* Found our initial offset.  We're done with reverse motion! */
                            if (newline_format == FF_DOS) {
                                offset_offset = i + (pos - fbuf) + 2;
                            } else {
                                offset_offset = i + (pos - fbuf) + 1;
                            }
                            break;
                        }
                    }
                    if ((offset < 0 && offset_offset >= 0) || (offset >= 0 && length_offset >= 0)) {
                        break;
                    }
                }
                /* We're at the beginning, and the negative offset indicates the exact number of lines in the file */
                if (offset < 0 && offset_offset < 0 && offset == count * -1) {
                    offset_offset = 0;
                }
            }
 
            /* Positve line offset */
            if (offset > 0) {
                int64_t count = 0;
                fseek(ff, 0, SEEK_SET);
                for (i = 0; i < flength; i += sizeof(fbuf)) {
                    char *pos;
                    if (i + sizeof(fbuf) >= flength) {
                        memset(fbuf, 0, sizeof(fbuf));
                    }
                    if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                        ast_log(LOG_ERROR, "Short read?!!\n");
                        fclose(ff);
                        return -1;
                    }
                    for (pos = fbuf; pos < fbuf + sizeof(fbuf); pos++) {
                        LINE_COUNTER(pos, newline_format, count);
 
                        if (count == offset) {
                            offset_offset = i + (pos - fbuf) + 1;
                            break;
                        }
                    }
                    if (offset_offset >= 0) {
                        break;
                    }
                }
            }
 
            if (offset_offset < 0) {
                ast_log(LOG_ERROR, "Offset '%s' refers to before the beginning of the file!\n", args.offset);
                fclose(ff);
                return -1;
            }
 
            if (length == 0) {
                length_offset = offset_offset;
            } else if (length == LLONG_MAX) {
                length_offset = flength;
            }
 
            /* Positive line length */
            if (length_offset < 0) {
                fseeko(ff, offset_offset, SEEK_SET);
                for (i = offset_offset; i < flength; i += sizeof(fbuf)) {
                    char *pos;
                    if (i + sizeof(fbuf) >= flength) {
                        memset(fbuf, 0, sizeof(fbuf));
                    }
                    if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                        ast_log(LOG_ERROR, "Short read?!!\n");
                        fclose(ff);
                        return -1;
                    }
                    for (pos = fbuf; pos < fbuf + sizeof(fbuf); pos++) {
                        LINE_COUNTER(pos, newline_format, current_length);
 
                        if (current_length == length) {
                            length_offset = i + (pos - fbuf) + 1;
                            break;
                        }
                    }
                    if (length_offset >= 0) {
                        break;
                    }
                }
                if (length_offset < 0) {
                    /* Exceeds length of file */
                    ast_debug(3, "Exceeds length of file? length=%" PRId64 ", count=%" PRId64 ", flength=%" PRId64 "\n", length, current_length, flength);
                    length_offset = flength;
                }
            }
 
            /* Have offset_offset and length_offset now */
            if (length_offset - offset_offset == vlength + (strchr(args.options, 'd') ? 0 : strlen(format2term(newline_format)))) {
                /* Simple case - replacement of text inline */
                fseeko(ff, offset_offset, SEEK_SET);
                if (fwrite(value, 1, vlength, ff) < vlength) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                } else if (!strchr(args.options, 'd') && fwrite(format2term(newline_format), 1, strlen(format2term(newline_format)), ff) < strlen(format2term(newline_format))) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                }
                fclose(ff);
            } else if (length_offset - offset_offset > vlength + (strchr(args.options, 'd') ? 0 : strlen(format2term(newline_format)))) {
                /* More complex case - need to shorten file */
                off_t cur;
                int64_t length_length = length_offset - offset_offset;
                size_t vlen = vlength + (strchr(args.options, 'd') ? 0 : strlen(format2term(newline_format)));
 
                ast_debug(3, "offset=%s/%" PRId64 ", length=%s/%" PRId64 " (%" PRId64 "), vlength=%" PRId64 ", flength=%" PRId64 "\n",
                    args.offset, offset_offset, args.length, length_offset, length_length, vlength, flength);
 
                fseeko(ff, offset_offset, SEEK_SET);
                if (fwrite(value, 1, vlength, ff) < vlength) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                    fclose(ff);
                    return -1;
                } else if (!strchr(args.options, 'd') && fwrite(format2term(newline_format), 1, vlen - vlength, ff) < vlen - vlength) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                    fclose(ff);
                    return -1;
                }
                while ((cur = ftello(ff)) < flength) {
                    if (cur < 0) {
                        ast_log(AST_LOG_ERROR, "Unable to determine last write position for '%s': %s\n", args.filename, strerror(errno));
                        fclose(ff);
                        return -1;
                    }
                    fseeko(ff, length_length - vlen, SEEK_CUR);
                    if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                        ast_log(LOG_ERROR, "Short read?!!\n");
                        fclose(ff);
                        return -1;
                    }
                    /* Seek to where we last stopped writing */
                    fseeko(ff, cur, SEEK_SET);
                    if (fwrite(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf)) {
                        ast_log(LOG_ERROR, "Short write?!!\n");
                        fclose(ff);
                        return -1;
                    }
                }
                fclose(ff);
                if (truncate(args.filename, flength - (length_length - vlen))) {
                    ast_log(LOG_ERROR, "Truncation of file failed: %s\n", strerror(errno));
                }
            } else {
                /* Most complex case - need to lengthen file */
                size_t vlen = vlength + (strchr(args.options, 'd') ? 0 : strlen(format2term(newline_format)));
                int64_t origlen = length_offset - offset_offset;
                off_t lastwritten = flength + vlen - origlen;
 
                ast_debug(3, "offset=%s/%" PRId64 ", length=%s/%" PRId64 ", vlength=%" PRId64 ", flength=%" PRId64 "\n",
                    args.offset, offset_offset, args.length, length_offset, vlength, flength);
 
                fseeko(ff, flength - sizeof(fbuf), SEEK_SET);
                while (offset_offset + sizeof(fbuf) < ftello(ff)) {
                    if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf)) {
                        ast_log(LOG_ERROR, "Short read?!!\n");
                        fclose(ff);
                        return -1;
                    }
                    fseeko(ff, sizeof(fbuf) - vlen - origlen, SEEK_CUR);
                    if (fwrite(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf)) {
                        ast_log(LOG_ERROR, "Short write?!!\n");
                        fclose(ff);
                        return -1;
                    }
                    if ((lastwritten = ftello(ff) - sizeof(fbuf)) < offset_offset + sizeof(fbuf)) {
                        break;
                    }
                    fseeko(ff, 2 * sizeof(fbuf) + vlen - origlen, SEEK_CUR);
                }
                fseek(ff, length_offset, SEEK_SET);
                if (fread(fbuf, 1, sizeof(fbuf), ff) < sizeof(fbuf) && !feof(ff)) {
                    ast_log(LOG_ERROR, "Short read?!!\n");
                    fclose(ff);
                    return -1;
                }
                fseek(ff, offset_offset, SEEK_SET);
                if (fwrite(value, 1, vlength, ff) < vlength) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                    fclose(ff);
                    return -1;
                } else if (!strchr(args.options, 'd') && fwrite(format2term(newline_format), 1, strlen(format2term(newline_format)), ff) < strlen(format2term(newline_format))) {
                    ast_log(LOG_ERROR, "Short write?!!\n");
                    fclose(ff);
                    return -1;
                } else {
                    off_t curpos = ftello(ff);
                    foplen = lastwritten - curpos;
                    if (fwrite(fbuf, 1, foplen, ff) < foplen) {
                        ast_log(LOG_ERROR, "Short write?!!\n");
                    }
                }
                fclose(ff);
            }
        }
    }
 
    return 0;
}
 
static struct ast_custom_function env_function = {
    .name = "ENV",
    .read = env_read,
    .write = env_write
};
 
static struct ast_custom_function stat_function = {
    .name = "STAT",
    .read = stat_read,
    .read_max = 12,
};
 
static struct ast_custom_function file_function = {
    .name = "FILE",
    .read2 = file_read,
    .write = file_write,
};
 
static struct ast_custom_function file_count_line_function = {
    .name = "FILE_COUNT_LINE",
    .read2 = file_count_line,
    .read_max = 12,
};
 
static struct ast_custom_function file_format_function = {
    .name = "FILE_FORMAT",
    .read2 = file_format,
    .read_max = 2,
};
 
static struct ast_custom_function file_dirname_function = {
    .name = "DIRNAME",
    .read = file_dirname,
    .read_max = 12,
};
 
static struct ast_custom_function file_basename_function = {
    .name = "BASENAME",
    .read = file_basename,
    .read_max = 12,
};
 
static int unload_module(void)
{
    int res = 0;
 
    res |= ast_custom_function_unregister(&env_function);
    res |= ast_custom_function_unregister(&stat_function);
    res |= ast_custom_function_unregister(&file_function);
    res |= ast_custom_function_unregister(&file_count_line_function);
    res |= ast_custom_function_unregister(&file_format_function);
    res |= ast_custom_function_unregister(&file_dirname_function);
    res |= ast_custom_function_unregister(&file_basename_function);
 
    return res;
}
 
static int load_module(void)
{
    int res = 0;
 
    res |= ast_custom_function_register(&env_function);
    res |= ast_custom_function_register_escalating(&stat_function, AST_CFE_READ);
    res |= ast_custom_function_register_escalating(&file_function, AST_CFE_BOTH);
    res |= ast_custom_function_register_escalating(&file_count_line_function, AST_CFE_READ);
    res |= ast_custom_function_register_escalating(&file_format_function, AST_CFE_READ);
    res |= ast_custom_function_register(&file_dirname_function);
    res |= ast_custom_function_register(&file_basename_function);
 
    return res;
}
 
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Environment/filesystem dialplan functions");