[PATCH 3/8] posix: Remove alloca usage for GLOB_BRACE on glob

[Adhemerval Zanella]

GNU GLOB_BRACE internal implementation constructs a new expression and
calls glob recursively.  It then requires a possible large temporary
buffer place the new pattern.

This patch removes the alloca/malloc usage and replaces it with
char_array.

Checked on x86_64-linux-gnu.
---
 posix/glob.c | 53 ++++++++++++++++++++++++++++------------------------
 1 file changed, 29 insertions(+), 24 deletions(-)

diff --git a/posix/glob.c b/posix/glob.c
index 8c6e1914c5..41e1aeacad 100644
--- a/posix/glob.c
+++ b/posix/glob.c
@@ -382,25 +382,23 @@ __glob (const char *pattern, int flags, int (*errfunc) 
(const char *, int),
           /* Allocate working buffer large enough for our work.  Note that
              we have at least an opening and closing brace.  */
           size_t firstc;
-          char *alt_start;
           const char *p;
           const char *next;
           const char *rest;
           size_t rest_len;
-          char *onealt;
-          size_t pattern_len = strlen (pattern) - 1;
-          int alloca_onealt = glob_use_alloca (alloca_used, pattern_len);
-          if (alloca_onealt)
-            onealt = alloca_account (pattern_len, alloca_used);
-          else
-            {
-              onealt = malloc (pattern_len);
-              if (onealt == NULL)
-                goto err_nospace;
-            }
+          struct char_array onealt;
 
           /* We know the prefix for all sub-patterns.  */
-          alt_start = mempcpy (onealt, pattern, begin - pattern);
+          ptrdiff_t onealtlen = begin - pattern;
+          if (!char_array_init_str_size (&onealt, pattern, onealtlen))
+            {
+              if (!(flags & GLOB_APPEND))
+                {
+                  pglob->gl_pathc = 0;
+                  pglob->gl_pathv = NULL;
+                }
+              goto err_nospace;
+            }
 
           /* Find the first sub-pattern and at the same time find the
              rest after the closing brace.  */
@@ -408,9 +406,7 @@ __glob (const char *pattern, int flags, int (*errfunc) 
(const char *, int),
           if (next == NULL)
             {
               /* It is an invalid expression.  */
-            illegal_brace:
-              if (__glibc_unlikely (!alloca_onealt))
-                free (onealt);
+              char_array_free (&onealt);
               flags &= ~GLOB_BRACE;
               goto no_brace;
             }
@@ -421,8 +417,12 @@ __glob (const char *pattern, int flags, int (*errfunc) 
(const char *, int),
             {
               rest = next_brace_sub (rest + 1, flags);
               if (rest == NULL)
-                /* It is an illegal expression.  */
-                goto illegal_brace;
+                {
+                  /* It is an illegal expression.  */
+                  char_array_free (&onealt);
+                  flags &= ~GLOB_BRACE;
+                  goto no_brace;
+                }
             }
           /* Please note that we now can be sure the brace expression
              is well-formed.  */
@@ -441,9 +441,16 @@ __glob (const char *pattern, int flags, int (*errfunc) 
(const char *, int),
               int result;
 
               /* Construct the new glob expression.  */
-              mempcpy (mempcpy (alt_start, p, next - p), rest, rest_len);
+              ptrdiff_t nextlen = next - p;
+              if (!char_array_replace_str_pos (&onealt, onealtlen, p, nextlen)
+                  || !char_array_replace_str_pos (&onealt, onealtlen + nextlen,
+                                                  rest, rest_len))
+                {
+                  char_array_free (&onealt);
+                  goto err_nospace;
+                }
 
-              result = __glob (onealt,
+              result = __glob (char_array_str (&onealt),
                                ((flags & ~(GLOB_NOCHECK | GLOB_NOMAGIC))
                                 | GLOB_APPEND),
                                errfunc, pglob);
@@ -451,8 +458,7 @@ __glob (const char *pattern, int flags, int (*errfunc) 
(const char *, int),
               /* If we got an error, return it.  */
               if (result && result != GLOB_NOMATCH)
                 {
-                  if (__glibc_unlikely (!alloca_onealt))
-                    free (onealt);
+                  char_array_free (&onealt);
                   if (!(flags & GLOB_APPEND))
                     {
                       globfree (pglob);
@@ -471,8 +477,7 @@ __glob (const char *pattern, int flags, int (*errfunc) 
(const char *, int),
               assert (next != NULL);
             }
 
-          if (__glibc_unlikely (!alloca_onealt))
-            free (onealt);
+          char_array_free (&onealt);
 
           if (pglob->gl_pathc != firstc)
             /* We found some entries.  */
-- 
2.25.1