Signed-off-by: Yumei Huang
---
util.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
util.h | 1 +
2 files changed, 91 insertions(+)
diff --git a/util.c b/util.c
index ab23463..c56f920 100644
--- a/util.c
+++ b/util.c
@@ -589,6 +589,96 @@ int write_file(const char *path, const char *buf)
return len == 0 ? 0 : -1;
}
+/**
+ * read_file() - Read contents of file into a NULL-terminated buffer
+ * @path: Path to file to read
+ * @buf: Buffer to store file contents
+ * @buf_size: Size of buffer
+ *
+ * Return: number of bytes read on success, negative error code on failure
+ */
+static ssize_t read_file(const char *path, char *buf, size_t buf_size)
+{
+ int fd = open(path, O_RDONLY | O_CLOEXEC);
+ size_t total_read = 0;
+
+ if (fd < 0)
+ return -errno;
+
+ if (!buf_size) {
+ close(fd);
+ return -EINVAL;
+ }
+
+ while (total_read < buf_size) {
+ ssize_t rc = read(fd, buf + total_read, buf_size - total_read);
+
+ if (rc < 0) {
+ int errno_save = errno;
+ close(fd);
+ return -errno_save;
+ }
+
+ if (rc == 0)
+ break;
+
+ total_read += rc;
+ }
+
+ close(fd);
+
+ if (total_read == buf_size) {
+ buf[buf_size - 1] = '\0';
+ return -ENOBUFS;
+ }
+
+ buf[total_read] = '\0';
+
+ return total_read;
+}
+
+/**
+ * read_file_integer() - Read an integer value from a file
+ * @path: Path to file to read
+ * @fallback: Default value if file can't be read
+ *
+ * Return: integer value, @fallback on failure
+ */
+intmax_t read_file_integer(const char *path, intmax_t fallback)
+{
+ ssize_t bytes_read;
+ char buf[BUFSIZ];
+ intmax_t value;
+ char *end;
+
+ bytes_read = read_file(path, buf, sizeof(buf));
+
+ if (bytes_read < 0)
+ goto error;
+
+ if (bytes_read == 0) {
+ debug("Empty file %s", path);
+ goto error;
+ }
+
+ errno = 0;
+ value = strtoimax(buf, &end, 10);
+ if (*end && *end != '\n') {
+ debug("Non-numeric content in %s", path);
+ goto error;
+ }
+ if (errno) {
+ debug("Out of range value in %s: %s", path, buf);
+ goto error;
+ }
+
+ return value;
+
+error:
+ debug("Using %"PRIdMAX" as default value", fallback);
+ return fallback;
+}
+
#ifdef __ia64__
/* Needed by do_clone() below: glibc doesn't export the prototype of __clone2(),
* use the description from clone(2).
diff --git a/util.h b/util.h
index a0b2ada..6dec14b 100644
--- a/util.h
+++ b/util.h
@@ -229,6 +229,7 @@ void pidfile_write(int fd, pid_t pid);
int __daemon(int pidfile_fd, int devnull_fd);
int fls(unsigned long x);
int write_file(const char *path, const char *buf);
+intmax_t read_file_integer(const char *path, intmax_t fallback);
int write_all_buf(int fd, const void *buf, size_t len);
int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip);
int read_all_buf(int fd, void *buf, size_t len);
--
2.51.1