implement uci revert

[project/uci.git] / util.c

diff --git a/util.c b/util.c
index c9be293..bcf65aa 100644 (file)
--- a/util.c
+++ b/util.c
@@ -16,6 +16,16 @@
  * This file contains wrappers to standard functions, which
  * throw exceptions upon failure.
  */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/file.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <fcntl.h>
+
+#define LINEBUF        32
+#define LINEBUF_MAX    4096
 
 static void *uci_malloc(struct uci_context *ctx, size_t size)
 {
@@ -49,4 +59,176 @@ static char *uci_strdup(struct uci_context *ctx, const char *str)
        return ptr;
 }
 
+static bool uci_validate_name(const char *str)
+{
+       if (!*str)
+               return false;
+
+       while (*str) {
+               if (!isalnum(*str) && (*str != '_'))
+                       return false;
+               str++;
+       }
+       return true;
+}
+
+static void uci_alloc_parse_context(struct uci_context *ctx)
+{
+       ctx->pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
+}
+
+int uci_parse_tuple(struct uci_context *ctx, char *str, char **package, char **section, char **option, char **value)
+{
+       char *last = NULL;
+
+       UCI_HANDLE_ERR(ctx);
+       UCI_ASSERT(ctx, str && package && section && option);
+
+       *package = strtok(str, ".");
+       if (!*package || !uci_validate_name(*package))
+               goto error;
+
+       last = *package;
+       *section = strtok(NULL, ".");
+       if (!*section)
+               goto lastval;
+
+       last = *section;
+       *option = strtok(NULL, ".");
+       if (!*option)
+               goto lastval;
+
+       last = *option;
+
+lastval:
+       last = strchr(last, '=');
+       if (last) {
+               if (!value)
+                       goto error;
+
+               *last = 0;
+               last++;
+               if (!*last)
+                       goto error;
+               *value = last;
+       }
+
+       if (*section && !uci_validate_name(*section))
+               goto error;
+       if (*option && !uci_validate_name(*option))
+               goto error;
+
+       goto done;
+
+error:
+       UCI_THROW(ctx, UCI_ERR_PARSE);
+
+done:
+       return 0;
+}
+
+
+static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
+{
+       struct uci_parse_context *pctx = ctx->pctx;
+
+       pctx->reason = reason;
+       pctx->byte = pos - pctx->buf;
+       UCI_THROW(ctx, UCI_ERR_PARSE);
+}
+
+
+/*
+ * Fetch a new line from the input stream and resize buffer if necessary
+ */
+static void uci_getln(struct uci_context *ctx, int offset)
+{
+       struct uci_parse_context *pctx = ctx->pctx;
+       char *p;
+       int ofs;
+
+       if (pctx->buf == NULL) {
+               pctx->buf = uci_malloc(ctx, LINEBUF);
+               pctx->bufsz = LINEBUF;
+       }
+
+       ofs = offset;
+       do {
+               p = &pctx->buf[ofs];
+               p[ofs] = 0;
+
+               p = fgets(p, pctx->bufsz - ofs, pctx->file);
+               if (!p || !*p)
+                       return;
+
+               ofs += strlen(p);
+               if (pctx->buf[ofs - 1] == '\n') {
+                       pctx->line++;
+                       pctx->buf[ofs - 1] = 0;
+                       return;
+               }
+
+               if (pctx->bufsz > LINEBUF_MAX/2)
+                       uci_parse_error(ctx, p, "line too long");
+
+               pctx->bufsz *= 2;
+               pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
+       } while (1);
+}
+
+/*
+ * open a stream and go to the right position
+ *
+ * note: when opening for write and seeking to the beginning of
+ * the stream, truncate the file
+ */
+static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
+{
+       struct stat statbuf;
+       FILE *file = NULL;
+       int fd, ret;
+       int mode = (write ? O_RDWR : O_RDONLY);
+
+       if (create)
+               mode |= O_CREAT;
+
+       if (!write && ((stat(filename, &statbuf) < 0) ||
+               ((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
+               UCI_THROW(ctx, UCI_ERR_NOTFOUND);
+       }
+
+       fd = open(filename, mode, UCI_FILEMODE);
+       if (fd <= 0)
+               goto error;
+
+       if (flock(fd, (write ? LOCK_EX : LOCK_SH)) < 0)
+               goto error;
+
+       ret = lseek(fd, 0, pos);
+
+       if (ret < 0)
+               goto error;
+
+       file = fdopen(fd, (write ? "w+" : "r"));
+       if (file)
+               goto done;
+
+error:
+       UCI_THROW(ctx, UCI_ERR_IO);
+done:
+       return file;
+}
+
+static void uci_close_stream(FILE *stream)
+{
+       int fd;
+
+       if (!stream)
+               return;
+
+       fd = fileno(stream);
+       flock(fd, LOCK_UN);
+       fclose(stream);
+}
+