X-Git-Url: https://git.hcoop.net/bpt/emacs.git/blobdiff_plain/b70d23ff742098877b929e8a4982d5e56f6513da..d3cefd1358e021cc4d510afb18916b067e6b1419:/lib/careadlinkat.c

diff --git a/lib/careadlinkat.c b/lib/careadlinkat.c
index 15ffe24c0f..cd4aa846dc 100644
--- a/lib/careadlinkat.c
+++ b/lib/careadlinkat.c
@@ -1,6 +1,6 @@
 /* Read symbolic links into a buffer without size limitation, relative to fd.
 
-   Copyright (C) 2001, 2003-2004, 2007, 2009-2011 Free Software Foundation,
+   Copyright (C) 2001, 2003-2004, 2007, 2009-2012 Free Software Foundation,
    Inc.
 
    This program is free software: you can redistribute it and/or modify
@@ -22,19 +22,12 @@
 
 #include "careadlinkat.h"
 
-#include "allocator.h"
-
 #include <errno.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
-/* Use the system functions, not the gnulib overrides, because this
-   module does not depend on GNU or POSIX semantics.  */
-#undef malloc
-#undef realloc
-
 /* Define this independently so that stdint.h is not a prerequisite.  */
 #ifndef SIZE_MAX
 # define SIZE_MAX ((size_t) -1)
@@ -44,23 +37,21 @@
 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
 #endif
 
-#if ! HAVE_READLINKAT
-/* Ignore FD.  Get the symbolic link value of FILENAME and put it into
-   BUFFER, with size BUFFER_SIZE.  This function acts like readlink
-   but has readlinkat's signature.  */
+#include "allocator.h"
+
+/* Get the symbolic link value of FILENAME and put it into BUFFER, with
+   size BUFFER_SIZE.  This function acts like readlink  but has
+   readlinkat's signature.  */
 ssize_t
 careadlinkatcwd (int fd, char const *filename, char *buffer,
                  size_t buffer_size)
 {
-  (void) fd;
+  /* FD must be AT_FDCWD here, otherwise the caller is using this
+     function in contexts for which it was not meant for.  */
+  if (fd != AT_FDCWD)
+    abort ();
   return readlink (filename, buffer, buffer_size);
 }
-#endif
-
-/* A standard allocator.  For now, only careadlinkat needs this, but
-   perhaps it should be moved to the allocator module.  */
-static struct allocator const standard_allocator =
-  { malloc, realloc, free, NULL };
 
 /* Assuming the current directory is FD, get the symbolic link value
    of FILENAME as a null-terminated string and put it into a buffer.
@@ -76,7 +67,10 @@ static struct allocator const standard_allocator =
    the returned value if it is nonnull and is not BUFFER.  A null
    ALLOC stands for the standard allocator.
 
-   The PREADLINKAT function specifies how to read links.
+   The PREADLINKAT function specifies how to read links.  It operates
+   like POSIX readlinkat()
+   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
+   but can assume that its first argument is the same as FD.
 
    If successful, return the buffer address; otherwise return NULL and
    set errno.  */
@@ -94,7 +88,7 @@ careadlinkat (int fd, char const *filename,
   char stack_buf[1024];
 
   if (! alloc)
-    alloc = &standard_allocator;
+    alloc = &stdlib_allocator;
 
   if (! buffer_size)
     {
@@ -138,16 +132,17 @@ careadlinkat (int fd, char const *filename,
 
           if (buf == stack_buf)
             {
-              char *b = (char *) alloc->malloc (link_size);
+              char *b = (char *) alloc->allocate (link_size);
+              buf_size = link_size;
               if (! b)
                 break;
               memcpy (b, buf, link_size);
               buf = b;
             }
-          else if (link_size < buf_size && buf != buffer && alloc->realloc)
+          else if (link_size < buf_size && buf != buffer && alloc->reallocate)
             {
               /* Shrink BUF before returning it.  */
-              char *b = (char *) alloc->realloc (buf, link_size);
+              char *b = (char *) alloc->reallocate (buf, link_size);
               if (b)
                 buf = b;
             }
@@ -162,14 +157,19 @@ careadlinkat (int fd, char const *filename,
         buf_size *= 2;
       else if (buf_size < buf_size_max)
         buf_size = buf_size_max;
+      else if (buf_size_max < SIZE_MAX)
+        {
+          errno = ENAMETOOLONG;
+          return NULL;
+        }
       else
         break;
-      buf = (char *) alloc->malloc (buf_size);
+      buf = (char *) alloc->allocate (buf_size);
     }
   while (buf);
 
   if (alloc->die)
-    alloc->die ();
+    alloc->die (buf_size);
   errno = ENOMEM;
   return NULL;
 }