add functions fc_safe_write_file_init/open/close

HISTORY

@@ -1,5 +1,5 @@
 
-Version 1.54  2021-09-22
+Version 1.54  2021-10-10
   * fast_allocator.[hc]: correct reclaim_interval logic
   * shared_func.[hc]: add functions getFileContentEx1 and getFileContent1
   * fc_queue.[hc]: add function fc_queue_timedpeek

src/common_define.h

@@ -280,6 +280,12 @@ typedef struct
     string_t s;
 } FilenameString;
 
+typedef struct {
+    char *filename;
+    char *tmp_filename;
+    int fd;
+} SafeWriteFileInfo;
+
 typedef void (*FreeDataFunc)(void *ptr);
 typedef int (*CompareFunc)(void *p1, void *p2);
 typedef void* (*MallocFunc)(size_t size);

src/shared_func.c

@@ -3630,3 +3630,27 @@ bool is_digital_string(const char *str)
 
     return true;
 }
+
+int fc_safe_write_file_init(SafeWriteFileInfo *fi,
+        const char *file_path, const char *redo_filename,
+        const char *tmp_filename)
+{
+    char full_filename[PATH_MAX];
+
+    snprintf(full_filename, sizeof(full_filename), "%s/%s",
+            file_path, redo_filename);
+    if ((fi->filename=fc_strdup(full_filename)) == NULL)
+    {
+        return ENOMEM;
+    }
+
+    snprintf(full_filename, sizeof(full_filename), "%s/%s",
+            file_path, tmp_filename);
+    if ((fi->tmp_filename=fc_strdup(full_filename)) == NULL)
+    {
+        return ENOMEM;
+    }
+
+    fi->fd = -1;
+    return 0;
+}

src/shared_func.h

@@ -1131,6 +1131,45 @@ int fc_check_filename(const string_t *filename, const char *caption);
  */
 bool is_digital_string(const char *str);
 
+int fc_safe_write_file_init(SafeWriteFileInfo *fi,
+        const char *file_path, const char *redo_filename,
+        const char *tmp_filename);
+
+static inline int fc_safe_write_file_open(SafeWriteFileInfo *fi)
+{
+    const int flags = O_WRONLY | O_CREAT | O_TRUNC;
+    int result;
+
+    if ((fi->fd=open(fi->tmp_filename, flags, 0644)) < 0) {
+        result = errno != 0 ? errno : EIO;
+        logError("file: "__FILE__", line: %d, "
+                "open file %s fail, errno: %d, error info: %s",
+                __LINE__, fi->tmp_filename, result, STRERROR(result));
+        return result;
+    } else {
+        return 0;
+    }
+}
+
+static inline int fc_safe_write_file_close(SafeWriteFileInfo *fi)
+{
+    int result;
+
+    close(fi->fd);
+    if (rename(fi->tmp_filename, fi->filename) != 0)
+    {
+        result = errno != 0 ? errno : EIO;
+        logError("file: "__FILE__", line: %d, "
+                "rename file \"%s\" to \"%s\" fail, "
+                "errno: %d, error info: %s", __LINE__,
+                fi->tmp_filename, fi->filename,
+                result, STRERROR(result));
+        return result;
+    } else {
+        return 0;
+    }
+}
+
 static inline int fc_check_realloc_iovec_array(
         iovec_array_t *array, const int target_size)
 {