@@ -397,6 +397,17 @@ extern void hex_init (void);
/* Save files used for communication between processes. */
#define PEX_SAVE_TEMPS 0x4
+/* Max number of alloca bytes per call before we must switch to malloc.
+
+ ?? Swiped from gnulib's regex_internal.h header. Is this actually
+ the case? This number seems arbitrary, though sane.
+
+ The OS usually guarantees only one guard page at the bottom of the stack,
+ and a page size can be as small as 4096 bytes. So we cannot safely
+ allocate anything larger than 4096 bytes. Also care for the possibility
+ of a few compiler-allocated temporary stack slots. */
+#define MAX_ALLOCA_SIZE 4032
+
/* Prepare to execute one or more programs, with standard output of
each program fed to standard input of the next.
FLAGS As above.
@@ -233,6 +233,7 @@ make_relative_prefix_1 (const char *progname, const char *bin_prefix,
int i, n, common;
int needed_len;
char *ret = NULL, *ptr, *full_progname;
+ char *alloc_ptr = NULL;
if (progname == NULL || bin_prefix == NULL || prefix == NULL)
return NULL;
@@ -256,7 +257,10 @@ make_relative_prefix_1 (const char *progname, const char *bin_prefix,
#ifdef HAVE_HOST_EXECUTABLE_SUFFIX
len += strlen (HOST_EXECUTABLE_SUFFIX);
#endif
- nstore = (char *) alloca (len);
+ if (len < MAX_ALLOCA_SIZE)
+ nstore = (char *) alloca (len);
+ else
+ alloc_ptr = nstore = (char *) malloc (len);
startp = endp = temp;
while (1)
@@ -312,12 +316,12 @@ make_relative_prefix_1 (const char *progname, const char *bin_prefix,
else
full_progname = strdup (progname);
if (full_progname == NULL)
- return NULL;
+ goto bailout;
prog_dirs = split_directories (full_progname, &prog_num);
free (full_progname);
if (prog_dirs == NULL)
- return NULL;
+ goto bailout;
bin_dirs = split_directories (bin_prefix, &bin_num);
if (bin_dirs == NULL)
@@ -395,6 +399,7 @@ make_relative_prefix_1 (const char *progname, const char *bin_prefix,
free_split_directories (prog_dirs);
free_split_directories (bin_dirs);
free_split_directories (prefix_dirs);
+ free (alloc_ptr);
return ret;
}