summaryrefslogtreecommitdiffstats
path: root/lib/fopen.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/fopen.c')
-rw-r--r--lib/fopen.c230
1 files changed, 230 insertions, 0 deletions
diff --git a/lib/fopen.c b/lib/fopen.c
new file mode 100644
index 0000000..a5b3ae3
--- /dev/null
+++ b/lib/fopen.c
@@ -0,0 +1,230 @@
+/* Open a stream to a file.
+ Copyright (C) 2007-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
+
+/* If the user's config.h happens to include <stdio.h>, let it include only
+ the system's <stdio.h> here, so that orig_fopen doesn't recurse to
+ rpl_fopen. */
+#define _GL_ALREADY_INCLUDING_STDIO_H
+#include <config.h>
+
+/* Get the original definition of fopen. It might be defined as a macro. */
+#include <stdio.h>
+#undef _GL_ALREADY_INCLUDING_STDIO_H
+
+static FILE *
+orig_fopen (const char *filename, const char *mode)
+{
+ return fopen (filename, mode);
+}
+
+/* Specification. */
+/* Write "stdio.h" here, not <stdio.h>, otherwise OSF/1 5.1 DTK cc eliminates
+ this include because of the preliminary #include <stdio.h> above. */
+#include "stdio.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+FILE *
+rpl_fopen (const char *filename, const char *mode)
+{
+ int open_direction;
+ int open_flags;
+#if GNULIB_FOPEN_GNU
+ bool open_flags_gnu;
+# define BUF_SIZE 80
+ char fdopen_mode_buf[BUF_SIZE + 1];
+#endif
+
+#if defined _WIN32 && ! defined __CYGWIN__
+ if (strcmp (filename, "/dev/null") == 0)
+ filename = "NUL";
+#endif
+
+ /* Parse the mode. */
+ open_direction = 0;
+ open_flags = 0;
+#if GNULIB_FOPEN_GNU
+ open_flags_gnu = false;
+#endif
+ {
+ const char *p = mode;
+#if GNULIB_FOPEN_GNU
+ char *q = fdopen_mode_buf;
+#endif
+
+ for (; *p != '\0'; p++)
+ {
+ switch (*p)
+ {
+ case 'r':
+ open_direction = O_RDONLY;
+#if GNULIB_FOPEN_GNU
+ if (q < fdopen_mode_buf + BUF_SIZE)
+ *q++ = *p;
+#endif
+ continue;
+ case 'w':
+ open_direction = O_WRONLY;
+ open_flags |= O_CREAT | O_TRUNC;
+#if GNULIB_FOPEN_GNU
+ if (q < fdopen_mode_buf + BUF_SIZE)
+ *q++ = *p;
+#endif
+ continue;
+ case 'a':
+ open_direction = O_WRONLY;
+ open_flags |= O_CREAT | O_APPEND;
+#if GNULIB_FOPEN_GNU
+ if (q < fdopen_mode_buf + BUF_SIZE)
+ *q++ = *p;
+#endif
+ continue;
+ case 'b':
+ /* While it is non-standard, O_BINARY is guaranteed by
+ gnulib <fcntl.h>. We can also assume that orig_fopen
+ supports the 'b' flag. */
+ open_flags |= O_BINARY;
+#if GNULIB_FOPEN_GNU
+ if (q < fdopen_mode_buf + BUF_SIZE)
+ *q++ = *p;
+#endif
+ continue;
+ case '+':
+ open_direction = O_RDWR;
+#if GNULIB_FOPEN_GNU
+ if (q < fdopen_mode_buf + BUF_SIZE)
+ *q++ = *p;
+#endif
+ continue;
+#if GNULIB_FOPEN_GNU
+ case 'x':
+ open_flags |= O_EXCL;
+ open_flags_gnu = true;
+ continue;
+ case 'e':
+ open_flags |= O_CLOEXEC;
+ open_flags_gnu = true;
+ continue;
+#endif
+ default:
+ break;
+ }
+#if GNULIB_FOPEN_GNU
+ /* The rest of the mode string can be a platform-dependent extension.
+ Copy it unmodified. */
+ {
+ size_t len = strlen (p);
+ if (len > fdopen_mode_buf + BUF_SIZE - q)
+ len = fdopen_mode_buf + BUF_SIZE - q;
+ memcpy (q, p, len);
+ q += len;
+ }
+#endif
+ break;
+ }
+#if GNULIB_FOPEN_GNU
+ *q = '\0';
+#endif
+ }
+
+#if FOPEN_TRAILING_SLASH_BUG
+ /* Fail if the mode requires write access and the filename ends in a slash,
+ as POSIX says such a filename must name a directory
+ <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13>:
+ "A pathname that contains at least one non-<slash> character and that
+ ends with one or more trailing <slash> characters shall not be resolved
+ successfully unless the last pathname component before the trailing
+ <slash> characters names an existing directory"
+ If the named file already exists as a directory, then if a mode that
+ requires write access is specified, fopen() must fail because POSIX
+ <https://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html>
+ says that it fails with errno = EISDIR in this case.
+ If the named file does not exist or does not name a directory, then
+ fopen() must fail since the file does not contain a '.' directory. */
+ {
+ size_t len = strlen (filename);
+ if (len > 0 && filename[len - 1] == '/')
+ {
+ int fd;
+ struct stat statbuf;
+ FILE *fp;
+
+ if (open_direction != O_RDONLY)
+ {
+ errno = EISDIR;
+ return NULL;
+ }
+
+ fd = open (filename, open_direction | open_flags,
+ S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
+ if (fd < 0)
+ return NULL;
+
+ if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+ {
+ close (fd);
+ errno = ENOTDIR;
+ return NULL;
+ }
+
+# if GNULIB_FOPEN_GNU
+ fp = fdopen (fd, fdopen_mode_buf);
+# else
+ fp = fdopen (fd, mode);
+# endif
+ if (fp == NULL)
+ {
+ int saved_errno = errno;
+ close (fd);
+ errno = saved_errno;
+ }
+ return fp;
+ }
+ }
+#endif
+
+#if GNULIB_FOPEN_GNU
+ if (open_flags_gnu)
+ {
+ int fd;
+ FILE *fp;
+
+ fd = open (filename, open_direction | open_flags,
+ S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
+ if (fd < 0)
+ return NULL;
+
+ fp = fdopen (fd, fdopen_mode_buf);
+ if (fp == NULL)
+ {
+ int saved_errno = errno;
+ close (fd);
+ errno = saved_errno;
+ }
+ return fp;
+ }
+#endif
+
+ return orig_fopen (filename, mode);
+}