X-Git-Url: https://git.cworth.org/git?p=tar;a=blobdiff_plain;f=gnu%2Fareadlinkat.c;fp=gnu%2Fareadlinkat.c;h=47fd1ba387c0f31a3ec29294ed52bfc2f4af5934;hp=0000000000000000000000000000000000000000;hb=de7372b23c3da92fbfaea2d1ac592f0b2ba87914;hpb=fbbfb9406a82e647ce27b6462b11a802fa48f31a
diff --git a/gnu/areadlinkat.c b/gnu/areadlinkat.c
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+/* -*- buffer-read-only: t -*- vi: set ro: */
+/* DO NOT EDIT! GENERATED AUTOMATICALLY! */
+/* areadlinkat.c -- readlinkat wrapper to return malloc'd link name
+ Unlike xreadlinkat, only call exit on failure to change directory.
+
+ Copyright (C) 2001, 2003-2007, 2009-2010 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see . */
+
+/* Written by Jim Meyering ,
+ and Bruno Haible ,
+ and Eric Blake . */
+
+#include
+
+/* Specification. */
+#include "areadlink.h"
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+#ifndef SSIZE_MAX
+# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
+#endif
+
+#if HAVE_READLINKAT
+
+/* The initial buffer size for the link value. A power of 2
+ detects arithmetic overflow earlier, but is not required. */
+enum {
+ INITIAL_BUF_SIZE = 1024
+};
+
+/* Call readlinkat to get the symbolic link value of FILENAME relative to FD.
+ Return a pointer to that NUL-terminated string in malloc'd storage.
+ If readlinkat fails, return NULL and set errno (although failure to
+ change directory will issue a diagnostic and exit).
+ If realloc fails, or if the link value is longer than SIZE_MAX :-),
+ return NULL and set errno to ENOMEM. */
+
+char *
+areadlinkat (int fd, char const *filename)
+{
+ /* Allocate the initial buffer on the stack. This way, in the common
+ case of a symlink of small size, we get away with a single small malloc()
+ instead of a big malloc() followed by a shrinking realloc(). */
+ char initial_buf[INITIAL_BUF_SIZE];
+
+ char *buffer = initial_buf;
+ size_t buf_size = sizeof initial_buf;
+
+ while (1)
+ {
+ /* Attempt to read the link into the current buffer. */
+ ssize_t link_length = readlinkat (fd, filename, buffer, buf_size);
+
+ /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1
+ with errno == ERANGE if the buffer is too small. */
+ if (link_length < 0 && errno != ERANGE)
+ {
+ if (buffer != initial_buf)
+ {
+ int saved_errno = errno;
+ free (buffer);
+ errno = saved_errno;
+ }
+ return NULL;
+ }
+
+ if ((size_t) link_length < buf_size)
+ {
+ buffer[link_length++] = '\0';
+
+ /* Return it in a chunk of memory as small as possible. */
+ if (buffer == initial_buf)
+ {
+ buffer = (char *) malloc (link_length);
+ if (buffer == NULL)
+ /* errno is ENOMEM. */
+ return NULL;
+ memcpy (buffer, initial_buf, link_length);
+ }
+ else
+ {
+ /* Shrink buffer before returning it. */
+ if ((size_t) link_length < buf_size)
+ {
+ char *smaller_buffer = (char *) realloc (buffer, link_length);
+
+ if (smaller_buffer != NULL)
+ buffer = smaller_buffer;
+ }
+ }
+ return buffer;
+ }
+
+ if (buffer != initial_buf)
+ free (buffer);
+ buf_size *= 2;
+ if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
+ {
+ errno = ENOMEM;
+ return NULL;
+ }
+ buffer = (char *) malloc (buf_size);
+ if (buffer == NULL)
+ /* errno is ENOMEM. */
+ return NULL;
+ }
+}
+
+#else /* !HAVE_READLINKAT */
+
+/* It is more efficient to change directories only once and call
+ areadlink, rather than repeatedly call the replacement
+ readlinkat. */
+
+# define AT_FUNC_NAME areadlinkat
+# define AT_FUNC_F1 areadlink
+# define AT_FUNC_POST_FILE_PARAM_DECLS /* empty */
+# define AT_FUNC_POST_FILE_ARGS /* empty */
+# define AT_FUNC_RESULT char *
+# define AT_FUNC_FAIL NULL
+# include "at-func.c"
+# undef AT_FUNC_NAME
+# undef AT_FUNC_F1
+# undef AT_FUNC_POST_FILE_PARAM_DECLS
+# undef AT_FUNC_POST_FILE_ARGS
+# undef AT_FUNC_RESULT
+# undef AT_FUNC_FAIL
+
+#endif /* !HAVE_READLINKAT */