Mesa (master): util: add os_read_file() helper
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gitlab-mirror at kemper.freedesktop.org
Tue Apr 30 15:41:16 UTC 2019
Module: Mesa
Branch: master
Commit: 316964709e21286c2af54e3afb3089d0fcce87c1
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=316964709e21286c2af54e3afb3089d0fcce87c1
Author: Eric Engestrom <eric.engestrom at intel.com>
Date: Mon Jan 28 15:44:12 2019 +0000
util: add os_read_file() helper
readN() taken from igt.
os_read_file() inspired by igt_sysfs_get()
Signed-off-by: Eric Engestrom <eric.engestrom at intel.com>
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
---
src/util/Makefile.sources | 2 +
src/util/meson.build | 1 +
src/util/os_file.c | 129 ++++++++++++++++++++++++++++++++++++++++++++++
src/util/os_file.h | 26 ++++++++++
4 files changed, 158 insertions(+)
diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
index 541cb6b85be..ad8c56d3d1b 100644
--- a/src/util/Makefile.sources
+++ b/src/util/Makefile.sources
@@ -29,6 +29,8 @@ MESA_UTIL_FILES := \
mesa-sha1.h \
os_time.c \
os_time.h \
+ os_file.c \
+ os_file.h \
os_misc.c \
os_misc.h \
u_process.c \
diff --git a/src/util/meson.build b/src/util/meson.build
index 322c75e5985..489b6df1710 100644
--- a/src/util/meson.build
+++ b/src/util/meson.build
@@ -52,6 +52,7 @@ files_mesa_util = files(
'mesa-sha1.h',
'os_time.c',
'os_time.h',
+ 'os_file.c',
'os_misc.c',
'os_misc.h',
'u_process.c',
diff --git a/src/util/os_file.c b/src/util/os_file.c
new file mode 100644
index 00000000000..cee9d22c8ec
--- /dev/null
+++ b/src/util/os_file.c
@@ -0,0 +1,129 @@
+/*
+ * Copyright 2019 Intel Corporation
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "os_file.h"
+
+#include <errno.h>
+
+#if defined(__linux__)
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+
+static ssize_t
+readN(int fd, char *buf, size_t len)
+{
+ int err = -ENODATA;
+ size_t total = 0;
+ do {
+ ssize_t ret = read(fd, buf + total, len - total);
+
+ if (ret < 0)
+ ret = -errno;
+
+ if (ret == -EINTR || ret == -EAGAIN)
+ continue;
+
+ if (ret <= 0)
+ break;
+
+ total += ret;
+ } while (total != len);
+
+ return total ? total : err;
+}
+
+static char *
+read_grow(int fd)
+{
+ size_t len = 64;
+
+ char *buf = malloc(len);
+ if (!buf) {
+ close(fd);
+ errno = -ENOMEM;
+ return NULL;
+ }
+
+ ssize_t read;
+ size_t offset = 0, remaining = len - 1;
+ while ((read = readN(fd, buf + offset, remaining)) == remaining) {
+ char *newbuf = realloc(buf, 2 * len);
+ if (!newbuf) {
+ free(buf);
+ close(fd);
+ errno = -ENOMEM;
+ return NULL;
+ }
+
+ buf = newbuf;
+ len *= 2;
+ offset += read;
+ remaining = len - offset - 1;
+ }
+
+ close(fd);
+
+ if (read > 0)
+ offset += read;
+
+ buf[offset] = '\0';
+
+ return buf;
+}
+
+char *
+os_read_file(const char *filename)
+{
+ size_t len = 0;
+
+ int fd = open(filename, O_RDONLY);
+ if (fd == -1) {
+ /* errno set by open() */
+ return NULL;
+ }
+
+ struct stat stat;
+ if (fstat(fd, &stat) == 0)
+ len = stat.st_size;
+
+ if (!len)
+ return read_grow(fd);
+
+ /* add NULL terminator */
+ len++;
+
+ char *buf = malloc(len);
+ if (!buf) {
+ close(fd);
+ errno = -ENOMEM;
+ return NULL;
+ }
+
+ ssize_t read = readN(fd, buf, len - 1);
+
+ close(fd);
+
+ if (read == -1)
+ return NULL;
+
+ buf[read] = '\0';
+
+ return buf;
+}
+
+#else
+
+char *
+os_read_file(const char *filename)
+{
+ errno = -ENOSYS;
+ return NULL;
+}
+
+#endif
diff --git a/src/util/os_file.h b/src/util/os_file.h
new file mode 100644
index 00000000000..2f97c19ed55
--- /dev/null
+++ b/src/util/os_file.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2019 Intel Corporation
+ * SPDX-License-Identifier: MIT
+ *
+ * File operations helpers
+ */
+
+#ifndef _OS_FILE_H_
+#define _OS_FILE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Read a file.
+ * Returns a char* that the caller must free(), or NULL and sets errno.
+ */
+char *
+os_read_file(const char *filename);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _OS_FILE_H_ */
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