file: use dynamic memory allocation for tempfile name

Allocating a 4KB stack space buffer just for formatting a tempfile name
does not seem ideal.

Fixes: aa46546794ac ("file: uci_file_commit: fix memory leak")
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

diff --git a/file.c b/file.c
index 5502a4286d7f8ffec4095e64dde61a140d5051cc..ce1acb2024bb1b1b7d7ea560879d7096a98f2304 100644 (file)
--- a/file.c
+++ b/file.c
@@ -33,10 +33,6 @@
 #include "uci.h"
 #include "uci_internal.h"
 
-#ifndef MAX_PATH
-#define MAX_PATH 4096
-#endif
-
 #define LINEBUF        32
 
 /*
@@ -727,10 +723,10 @@ static void uci_file_commit(struct uci_context *ctx, struct uci_package **packag
        FILE *f1, *f2 = NULL;
        char *volatile name = NULL;
        char *volatile path = NULL;
-       char filename[MAX_PATH] = {0};
+       char *filename = NULL;
        struct stat statbuf;
        volatile bool do_rename = false;
-       int fd;
+       int fd, sz;
 
        if (!p->path) {
                if (overwrite)
@@ -739,8 +735,9 @@ static void uci_file_commit(struct uci_context *ctx, struct uci_package **packag
                        UCI_THROW(ctx, UCI_ERR_INVAL);
        }
 
-       if (snprintf(filename, MAX_PATH, "%s/.%s.uci-XXXXXX", ctx->confdir, p->e.name) < 0)
-               UCI_THROW(ctx, UCI_ERR_MEM);
+       sz = snprintf(NULL, 0, "%s/.%s.uci-XXXXXX", ctx->confdir, p->e.name);
+       filename = alloca(sz + 1);
+       snprintf(filename, sz + 1, "%s/.%s.uci-XXXXXX", ctx->confdir, p->e.name);
 
        /* open the config file for writing now, so that it is locked */
        f1 = uci_open_stream(ctx, p->path, NULL, SEEK_SET, true, true);