1 /* read-file.c -- read file contents into a string
2 Copyright (C) 2006, 2009-2015 Free Software Foundation, Inc.
3 Written by Simon Josefsson and Bruno Haible.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <http://www.gnu.org/licenses/>. */
20 #include "read-file.h"
31 /* Get malloc, realloc, free. */
37 /* Read a STREAM and return a newly allocated string with the content,
38 and set *LENGTH to the length of the string. The string is
39 zero-terminated, but the terminating zero byte is not counted in
40 *LENGTH. On errors, *LENGTH is undefined, errno preserves the
41 values set by system functions (if any), and NULL is returned. */
43 fread_file (FILE *stream, size_t *length)
46 size_t alloc = BUFSIZ;
48 /* For a regular file, allocate a buffer that has exactly the right
49 size. This avoids the need to do dynamic reallocations later. */
53 if (fstat (fileno (stream), &st) >= 0 && S_ISREG (st.st_mode))
55 off_t pos = ftello (stream);
57 if (pos >= 0 && pos < st.st_size)
59 off_t alloc_off = st.st_size - pos;
61 /* '1' below, accounts for the trailing NUL. */
62 if (SIZE_MAX - 1 < alloc_off)
68 alloc = alloc_off + 1;
73 if (!(buf = malloc (alloc)))
74 return NULL; /* errno is ENOMEM. */
77 size_t size = 0; /* number of bytes read so far */
82 /* This reads 1 more than the size of a regular file
83 so that we get eof immediately. */
84 size_t requested = alloc - size;
85 size_t count = fread (buf + size, 1, requested, stream);
88 if (count != requested)
94 /* Shrink the allocated memory if possible. */
97 char *smaller_buf = realloc (buf, size + 1);
98 if (smaller_buf != NULL)
110 if (alloc == SIZE_MAX)
116 if (alloc < SIZE_MAX - alloc / 2)
117 alloc = alloc + alloc / 2;
121 if (!(new_buf = realloc (buf, alloc)))
138 internal_read_file (const char *filename, size_t *length, const char *mode)
140 FILE *stream = fopen (filename, mode);
147 out = fread_file (stream, length);
151 if (fclose (stream) != 0)
165 /* Open and read the contents of FILENAME, and return a newly
166 allocated string with the content, and set *LENGTH to the length of
167 the string. The string is zero-terminated, but the terminating
168 zero byte is not counted in *LENGTH. On errors, *LENGTH is
169 undefined, errno preserves the values set by system functions (if
170 any), and NULL is returned. */
172 read_file (const char *filename, size_t *length)
174 return internal_read_file (filename, length, "r");
177 /* Open (on non-POSIX systems, in binary mode) and read the contents
178 of FILENAME, and return a newly allocated string with the content,
179 and set LENGTH to the length of the string. The string is
180 zero-terminated, but the terminating zero byte is not counted in
181 the LENGTH variable. On errors, *LENGTH is undefined, errno
182 preserves the values set by system functions (if any), and NULL is
185 read_binary_file (const char *filename, size_t *length)
187 return internal_read_file (filename, length, "rb");