shl: add shl_read_file() helper

This reads in a complete file as a string and returns it to the caller.
The string is 0 terminated (which isn't guaranteed by mmap()) so this
helper is needed if we have to work with APIs that don't accept buffer
lengths.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/src/shl_misc.h b/src/shl_misc.h
index 9aa1920..d90fd22 100644
--- a/src/shl_misc.h
+++ b/src/shl_misc.h
@@ -37,6 +37,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -262,6 +263,62 @@ static inline unsigned int shl_string_list_count(char **list, bool ignore_empty)
 	return num;
 }
 
+/* reads a whole file into a buffer with 0-termination */
+static inline int shl_read_file(const char *path, char **out, size_t *size)
+{
+	FILE *ffile;
+	ssize_t len;
+	char *buf;
+	int ret;
+
+	if (!path || !out)
+		return -EINVAL;
+
+	errno = 0;
+
+	ffile = fopen(path, "rb");
+	if (!ffile)
+		return -errno;
+
+	if (fseek(ffile, 0, SEEK_END) != 0) {
+		ret = -errno;
+		goto err_close;
+	}
+
+	len = ftell(ffile);
+	if (len < 0) {
+		ret = -errno;
+		goto err_close;
+	}
+
+	rewind(ffile);
+
+	buf = malloc(len + 1);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto err_close;
+	}
+
+	errno = 0;
+	if (len && len != fread(buf, 1, len, ffile)) {
+		ret = errno ? -errno : -EFAULT;
+		goto err_free;
+	}
+
+	buf[len] = 0;
+	*out = buf;
+	if (size)
+		*size = len;
+	ret = 0;
+	goto err_close;
+
+err_free:
+	free(buf);
+err_close:
+	fclose(ffile);
+	return ret;
+}
+
 /* TODO: xkbcommon should provide these flags!
  * We currently copy them into each library API we use so we need  to keep
  * them in sync. Currently, they're used in uterm-input and tsm-vte. */