X-Git-Url: https://jxself.org/git/?p=carl9170fw.git;a=blobdiff_plain;f=config%2Fconfdata.c;fp=config%2Fconfdata.c;h=da208c47fcb844e3101382fdf38dcc9f773d24b8;hp=da98566ccc6a45e68f1be3b03e7383831a7eb1a0;hb=42306a155d227ba90624c190a28344d61d566f46;hpb=04d2c0bc4dc1b10c5824fa54ceee7ee3547ca880

diff --git a/config/confdata.c b/config/confdata.c
index da98566..da208c4 100644
--- a/config/confdata.c
+++ b/config/confdata.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
  */
 
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <ctype.h>
 #include <errno.h>
@@ -36,6 +37,52 @@ static bool is_dir(const char *path)
 	return S_ISDIR(st.st_mode);
 }
 
+/* return true if the given two files are the same, false otherwise */
+static bool is_same(const char *file1, const char *file2)
+{
+	int fd1, fd2;
+	struct stat st1, st2;
+	void *map1, *map2;
+	bool ret = false;
+
+	fd1 = open(file1, O_RDONLY);
+	if (fd1 < 0)
+		return ret;
+
+	fd2 = open(file2, O_RDONLY);
+	if (fd2 < 0)
+		goto close1;
+
+	ret = fstat(fd1, &st1);
+	if (ret)
+		goto close2;
+	ret = fstat(fd2, &st2);
+	if (ret)
+		goto close2;
+
+	if (st1.st_size != st2.st_size)
+		goto close2;
+
+	map1 = mmap(NULL, st1.st_size, PROT_READ, MAP_PRIVATE, fd1, 0);
+	if (map1 == MAP_FAILED)
+		goto close2;
+
+	map2 = mmap(NULL, st2.st_size, PROT_READ, MAP_PRIVATE, fd2, 0);
+	if (map2 == MAP_FAILED)
+		goto close2;
+
+	if (bcmp(map1, map2, st1.st_size))
+		goto close2;
+
+	ret = true;
+close2:
+	close(fd2);
+close1:
+	close(fd1);
+
+	return ret;
+}
+
 /*
  * Create the parent directory of the given path.
  *
@@ -934,6 +981,13 @@ next:
 	fclose(out);
 
 	if (*tmpname) {
+		if (is_same(name, tmpname)) {
+			conf_message("No change to %s", name);
+			unlink(tmpname);
+			sym_set_change_count(0);
+			return 0;
+		}
+
 		snprintf(oldname, sizeof(oldname), "%s.old", name);
 		rename(name, oldname);
 		if (rename(tmpname, name))