[PATCH] argp-help: Get rid of alloca.

[Joe Simmons-Talbott <josimmon@redhat.com>]

Replace alloca with a scratch_buffer to avoid potential stack overflow.

Checked on x86_64-linux-gnu
---
 argp/argp-help.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/argp/argp-help.c b/argp/argp-help.c
index d019ed58d2..a5982334f6 100644
--- a/argp/argp-help.c
+++ b/argp/argp-help.c
@@ -40,6 +40,7 @@ char *alloca ();
 # endif
 #endif
 
+#include <scratch_buffer.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -1450,8 +1451,17 @@ hol_usage (struct hol *hol, argp_fmtstream_t stream)
     {
       unsigned nentries;
       struct hol_entry *entry;
-      char *short_no_arg_opts = alloca (strlen (hol->short_options) + 1);
-      char *snao_end = short_no_arg_opts;
+      struct scratch_buffer buf;
+      scratch_buffer_init (&buf);
+      char *short_no_arg_opts;
+      char *snao_end;
+
+      if (!scratch_buffer_set_array_size (&buf, 1,
+					   strlen (hol->short_options) + 1))
+        return;
+      short_no_arg_opts = buf.data;
+      snao_end = short_no_arg_opts;
+	
 
       /* First we put a list of short options without arguments.  */
       for (entry = hol->entries, nentries = hol->num_entries
@@ -1478,6 +1488,8 @@ hol_usage (struct hol *hol, argp_fmtstream_t stream)
 	   ; entry++, nentries--)
 	hol_entry_long_iterate (entry, usage_long_opt,
 				entry->argp->argp_domain, stream);
+
+      scratch_buffer_free (&buf);
     }
 }
 \f
@@ -1698,7 +1710,13 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
     {
       int first_pattern = 1, more_patterns;
       size_t num_pattern_levels = argp_args_levels (argp);
-      char *pattern_levels = alloca (num_pattern_levels);
+      struct scratch_buffer buf;
+      scratch_buffer_init (&buf);
+      char *pattern_levels;
+
+      if (!scratch_buffer_set_array_size (&buf, 1, num_pattern_levels))
+        return;
+      pattern_levels = buf.data;
 
       memset (pattern_levels, 0, num_pattern_levels);
 
@@ -1746,6 +1764,8 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
 	  first_pattern = 0;
 	}
       while (more_patterns);
+
+      scratch_buffer_free (&buf);
     }
 
   if (flags & ARGP_HELP_PRE_DOC)
-- 
2.39.2