generates files with temporary name and only overwites on change

3 files changed, 158 insertions, 40 deletions

diff --git a/src/duk-libdom.c b/src/duk-libdom.c
index bc27dfc..3e2fbe4 100644
--- a/src/duk-libdom.c
+++ b/src/duk-libdom.c
@@ -366,7 +366,7 @@ static FILE *open_header(struct interface_map *interface_map, const char *name)
         snprintf(fname, fnamel, "%s.h", name);
 
         /* open output file */
-        hdrf = genb_fopen(fname, "w");
+        hdrf = genb_fopen_tmp(fname);
         free(fname);
         if (hdrf == NULL) {
                 return NULL;
@@ -387,8 +387,17 @@ static FILE *open_header(struct interface_map *interface_map, const char *name)
         return hdrf;
 }
 
-static int close_header(struct interface_map *interface_map, FILE *hdrf)
+static int close_header(struct interface_map *interface_map,
+                        FILE *hdrf,
+                        const char *name)
 {
+        char *fname;
+        int fnamel;
+
+        fnamel = strlen(name) + 4;
+        fname = malloc(fnamel);
+        snprintf(fname, fnamel, "%s.h", name);
+
         fprintf(hdrf, "\n#endif\n");
 
         /* binding postface */
@@ -396,7 +405,8 @@ static int close_header(struct interface_map *interface_map, FILE *hdrf)
                      interface_map->binding_node,
                      GENBIND_NODE_TYPE_POSTFACE);
 
-        fclose(hdrf);
+        genb_fclose_tmp(hdrf, fname);
+        free(fname);
 
         return 0;
 }
@@ -1056,7 +1066,7 @@ static int output_interface(struct interface_map *interface_map,
                  "%s.c", interfacee->class_name);
 
         /* open output file */
-        ifacef = genb_fopen(interfacee->filename, "w");
+        ifacef = genb_fopen_tmp(interfacee->filename);
         if (ifacef == NULL) {
                 return -1;
         }
@@ -1131,7 +1141,7 @@ static int output_interface(struct interface_map *interface_map,
                      GENBIND_NODE_TYPE_POSTFACE);
 
 op_error:
-        fclose(ifacef);
+        genb_fclose_tmp(ifacef, interfacee->filename);
 
         return res;
 }
@@ -1193,7 +1203,7 @@ output_private_header(struct interface_map *interface_map)
 
         }
 
-        close_header(interface_map, privf);
+        close_header(interface_map, privf, "private");
 
         return 0;
 }
@@ -1249,7 +1259,7 @@ output_prototype_header(struct interface_map *interface_map)
                 fprintf(protof, ";\n\n");
         }
 
-        close_header(interface_map, protof);
+        close_header(interface_map, protof, "prototype");
 
         return 0;
 }
@@ -1264,7 +1274,7 @@ output_makefile(struct interface_map *interface_map)
         FILE *makef;
 
         /* open output file */
-        makef = genb_fopen("Makefile", "w");
+        makef = genb_fopen_tmp("Makefile");
         if (makef == NULL) {
                 return -1;
         }
@@ -1286,7 +1296,7 @@ output_makefile(struct interface_map *interface_map)
         }
         fprintf(makef, "\nNSGENBIND_PREFIX:=%s\n", options->outdirname);
 
-        fclose(makef);
+        genb_fclose_tmp(makef, "Makefile");
 
         return 0;
 }
@@ -1331,7 +1341,7 @@ output_binding_header(struct interface_map *interface_map)
         fprintf(bindf,
                 "duk_ret_t %s_create_prototypes(duk_context *ctx);\n", DLPFX);
 
-        close_header(interface_map, bindf);
+        close_header(interface_map, bindf, "binding");
 
         return 0;
 }
@@ -1352,7 +1362,7 @@ output_binding_src(struct interface_map *interface_map)
         char *proto_name;
 
         /* open output file */
-        bindf = genb_fopen("binding.c", "w");
+        bindf = genb_fopen_tmp("binding.c");
         if (bindf == NULL) {
                 return -1;
         }
@@ -1523,7 +1533,8 @@ output_binding_src(struct interface_map *interface_map)
                      interface_map->binding_node,
                      GENBIND_NODE_TYPE_POSTFACE);
 
-        fclose(bindf);
+        genb_fclose_tmp(bindf, "binding.c");
+
         return 0;
 }
 
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
-
diff --git a/src/utils.h b/src/utils.h
index b37d755..508d1c1 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -22,6 +22,20 @@ char *genb_fpath(const char *fname);
  */
 FILE *genb_fopen(const char *fname, const char *mode);
 
+/**
+ * Open file allowing for output path prefix
+ *
+ * file is opened for reading/writing with a temporary suffix allowing for the
+ * matching close call to check the output is different before touching the
+ * target file.
+ */
+FILE *genb_fopen_tmp(const char *fname);
+
+/**
+ * Close file opened with genb_fopen
+ */
+int genb_fclose_tmp(FILE *filef, const char *fname);
+
 #ifdef _WIN32
 #define NEED_STRNDUP 1
 char *strndup(const char *s, size_t n);