generates files with temporary name and only overwites on change

1 files changed, 121 insertions, 28 deletions

diff --git a/src/utils.c b/src/utils.c
index 9e50a93..1e8ec23 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1,3 +1,11 @@
+/* utility functions
+ *
+ * This file is part of nsgenbind.
+ * Published under the MIT License,
+ *                http://www.opensource.org/licenses/mit-license.php
+ * Copyright 2015 Vincent Sanders <vince@netsurf-browser.org>
+ */
+
 #include <stdio.h>
 #include <string.h>
 #include <stdbool.h>
@@ -10,34 +18,120 @@
 /* exported function documented in utils.h */
 char *genb_fpath(const char *fname)
 {
-    char *fpath;
-    int fpathl;
+        char *fpath;
+        int fpathl;
+
+        fpathl = strlen(options->outdirname) + strlen(fname) + 2;
+        fpath = malloc(fpathl);
+        snprintf(fpath, fpathl, "%s/%s", options->outdirname, fname);
+
+        return fpath;
+}
+
+static char *genb_fpath_tmp(const char *fname)
+{
+        char *fpath;
+        int fpathl;
 
-    fpathl = strlen(options->outdirname) + strlen(fname) + 2;
-    fpath = malloc(fpathl);
-    snprintf(fpath, fpathl, "%s/%s", options->outdirname, fname);
+        fpathl = strlen(options->outdirname) + strlen(fname) + 3;
+        fpath = malloc(fpathl);
+        snprintf(fpath, fpathl, "%s/%s~", options->outdirname, fname);
 
-    return fpath;
+        return fpath;
 }
 
 /* exported function documented in utils.h */
 FILE *genb_fopen(const char *fname, const char *mode)
 {
-    char *fpath;
-    FILE *filef;
+        char *fpath;
+        FILE *filef;
+
+        fpath = genb_fpath(fname);
+
+        filef = fopen(fpath, mode);
+        if (filef == NULL) {
+                fprintf(stderr, "Error: unable to open file %s (%s)\n",
+                        fpath, strerror(errno));
+                free(fpath);
+                return NULL;
+        }
+        free(fpath);
+
+        return filef;
+}
+
+/* exported function documented in utils.h */
+FILE *genb_fopen_tmp(const char *fname)
+{
+        char *fpath;
+        FILE *filef;
+
+        fpath = genb_fpath_tmp(fname);
+
+        filef = fopen(fpath, "w+");
+        if (filef == NULL) {
+                fprintf(stderr, "Error: unable to open file %s (%s)\n",
+                        fpath, strerror(errno));
+                free(fpath);
+                return NULL;
+        }
+        free(fpath);
 
-    fpath = genb_fpath(fname);
+        return filef;
+}
 
-    filef = fopen(fpath, mode);
-    if (filef == NULL) {
-        fprintf(stderr, "Error: unable to open file %s (%s)\n",
-                fpath, strerror(errno));
+int genb_fclose_tmp(FILE *filef_tmp, const char *fname)
+{
+        char *fpath;
+        char *tpath;
+        FILE *filef;
+        char tbuf[1024];
+        char fbuf[1024];
+        size_t trd;
+        size_t frd;
+
+        fpath = genb_fpath(fname);
+        tpath = genb_fpath_tmp(fname);
+
+        filef = fopen(fpath, "r");
+        if (filef == NULL) {
+                /* unable to open target file for comparison */
+
+                fclose(filef_tmp); /*  close tmpfile */
+
+                remove(fpath);
+                rename(tpath, fpath);
+        } else {
+                rewind(filef_tmp);
+
+                frd = fread(fbuf, 1, 1024, filef);
+                while (frd != 0) {
+                        trd = fread(tbuf, 1, frd, filef_tmp);
+                        if ((trd != frd) ||
+                            (memcmp(tbuf, fbuf, trd) != 0)) {
+                                /* file doesnt match */
+                                fclose(filef_tmp);
+
+                                remove(fpath);
+                                rename(tpath, fpath);
+
+                                goto close_done;
+                        }
+
+                        frd = fread(fbuf, 1, 1024, filef);
+                }
+
+                /* was the same kill temporary file */
+                fclose(filef_tmp);
+                fclose(filef);
+                remove(tpath);
+        }
+
+close_done:
         free(fpath);
-        return NULL;
-    }
-    free(fpath);
+        free(tpath);
 
-    return filef;
+        return 0;
 }
 
 
@@ -45,20 +139,19 @@ FILE *genb_fopen(const char *fname, const char *mode)
 
 char *strndup(const char *s, size_t n)
 {
-	size_t len;
-	char *s2;
+        size_t len;
+        char *s2;
 
-	for (len = 0; len != n && s[len]; len++)
-		continue;
+        for (len = 0; len != n && s[len]; len++)
+                continue;
 
-	s2 = malloc(len + 1);
-	if (!s2)
-		return 0;
+        s2 = malloc(len + 1);
+        if (!s2)
+                return 0;
 
-	memcpy(s2, s, len);
-	s2[len] = 0;
-	return s2;
+        memcpy(s2, s, len);
+        s2[len] = 0;
+        return s2;
 }
 
 #endif
-