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-rw-r--r--util-src/pposix.c94
1 files changed, 49 insertions, 45 deletions
diff --git a/util-src/pposix.c b/util-src/pposix.c
index 4b4552f5..e70a9d7f 100644
--- a/util-src/pposix.c
+++ b/util-src/pposix.c
@@ -13,7 +13,7 @@
* POSIX support functions for Lua
*/
-#define MODULE_VERSION "0.3.6"
+#define MODULE_VERSION "0.4.0"
#if defined(__linux__)
@@ -730,62 +730,66 @@ int lc_meminfo(lua_State *L) {
}
#endif
-/* File handle extraction blatantly stolen from
- * https://github.com/rrthomas/luaposix/blob/master/lposix.c#L631
- * */
+/*
+ * Append some data to a file handle
+ * Attempt to allocate space first
+ * Truncate to original size on failure
+ */
+int lc_atomic_append(lua_State *L) {
+ int err;
+ size_t len;
-int lc_fallocate(lua_State *L) {
- int ret;
- off_t offset, len;
FILE *f = *(FILE **) luaL_checkudata(L, 1, LUA_FILEHANDLE);
+ const char *data = luaL_checklstring(L, 2, &len);
- if(f == NULL) {
- return luaL_error(L, "attempt to use a closed file");
- }
-
- offset = luaL_checkinteger(L, 2);
- len = luaL_checkinteger(L, 3);
+ off_t offset = ftell(f);
#if defined(__linux__)
- errno = 0;
- ret = fallocate(fileno(f), FALLOC_FL_KEEP_SIZE, offset, len);
-
- if(ret == 0) {
- lua_pushboolean(L, 1);
- return 1;
- }
-
- /* Some old versions of Linux apparently use the return value instead of errno */
- if(errno == 0) {
- errno = ret;
- }
+ /* Try to allocate space without changing the file size. */
+ if((err = fallocate(fileno(f), FALLOC_FL_KEEP_SIZE, offset, len))) {
+ if(errno != 0) {
+ /* Some old versions of Linux apparently use the return value instead of errno */
+ err = errno;
+ }
+ switch(err) {
+ case ENOSYS: /* Kernel doesn't implement fallocate */
+ case EOPNOTSUPP: /* Filesystem doesn't support it */
+ /* Ignore and proceed to try to write */
+ break;
- if(errno != ENOSYS && errno != EOPNOTSUPP) {
- lua_pushnil(L);
- lua_pushstring(L, strerror(errno));
- return 2;
+ case ENOSPC: /* No space left */
+ default: /* Other issues */
+ lua_pushnil(L);
+ lua_pushstring(L, strerror(err));
+ lua_pushinteger(L, err);
+ return 3;
+ }
}
-
#endif
- ret = posix_fallocate(fileno(f), offset, len);
-
- if(ret == 0) {
- lua_pushboolean(L, 1);
- return 1;
+ if(fwrite(data, sizeof(char), len, f) == len) {
+ if(fflush(f) == 0) {
+ lua_pushboolean(L, 1); /* Great success! */
+ return 1;
+ } else {
+ err = errno;
+ }
} else {
- lua_pushnil(L);
- lua_pushstring(L, strerror(ret));
+ err = ferror(f);
+ }
- /* posix_fallocate() can leave a bunch of NULs at the end, so we cut that
- * this assumes that offset == length of the file */
- if(ftruncate(fileno(f), offset) != 0) {
- lua_pushstring(L, strerror(errno));
- return 3;
- }
+ fseek(f, offset, SEEK_SET);
- return 2;
+ /* Cut partially written data */
+ if(ftruncate(fileno(f), offset)) {
+ /* The file is now most likely corrupted, throw hard error */
+ return luaL_error(L, "atomic_append() failed in ftruncate(): %s", strerror(errno));
}
+
+ lua_pushnil(L);
+ lua_pushstring(L, strerror(err));
+ lua_pushinteger(L, err);
+ return 3;
}
/* Register functions */
@@ -827,7 +831,7 @@ int luaopen_util_pposix(lua_State *L) {
{ "meminfo", lc_meminfo },
#endif
- { "fallocate", lc_fallocate },
+ { "atomic_append", lc_atomic_append },
{ NULL, NULL }
};