fopen: Fix the trailing slash workaround.

* lib/fopen.c (rpl_fopen): Parse the mode string. Recognize "r+" as a
write access. Pass the right flags to open().
* tests/test-fopen.h (test_fopen): Add a few more tests on directories.

1 files changed, 39 insertions, 3 deletions

diff --git a/lib/fopen.c b/lib/fopen.c
index a3128fa8b7..ad6511d2c7 100644
--- a/lib/fopen.c
+++ b/lib/fopen.c
@@ -47,11 +47,47 @@ orig_fopen (const char *filename, const char *mode)
 FILE *
 rpl_fopen (const char *filename, const char *mode)
 {
+  int open_direction;
+  int open_flags_standard;
+
 #if defined _WIN32 && ! defined __CYGWIN__
   if (strcmp (filename, "/dev/null") == 0)
     filename = "NUL";
 #endif
 
+  /* Parse the mode.  */
+  open_direction = 0;
+  open_flags_standard = 0;
+  {
+    const char *m;
+
+    for (m = mode; *m != '\0'; m++)
+      {
+        switch (*m)
+          {
+          case 'r':
+            open_direction = O_RDONLY;
+            continue;
+          case 'w':
+            open_direction = O_WRONLY;
+            open_flags_standard |= O_CREAT | O_TRUNC;
+            continue;
+          case 'a':
+            open_direction = O_WRONLY;
+            open_flags_standard |= O_CREAT | O_APPEND;
+            continue;
+          case 'b':
+            continue;
+          case '+':
+            open_direction = O_RDWR;
+            continue;
+          default:
+            break;
+          }
+        break;
+      }
+  }
+
 #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
@@ -74,13 +110,13 @@ rpl_fopen (const char *filename, const char *mode)
         struct stat statbuf;
         FILE *fp;
 
-        if (mode[0] == 'w' || mode[0] == 'a')
+        if (open_direction != O_RDONLY)
           {
             errno = EISDIR;
             return NULL;
           }
 
-        fd = open (filename, O_RDONLY);
+        fd = open (filename, open_direction | open_flags_standard);
         if (fd < 0)
           return NULL;
 
@@ -101,7 +137,7 @@ rpl_fopen (const char *filename, const char *mode)
         return fp;
       }
   }
-# endif
+#endif
 
   return orig_fopen (filename, mode);
 }