perf tools: Add filename__read_str util function

Adding filename__read_str util function to read
text file and return it in the char array.

The interface is:
  int filename__read_str(const char *filename, char **buf, size_t *sizep)

  Returns 0/-1 if the read suceeded/fail respectively.

  buf  - place to store the data pointer
  size - place to store data size

v2 change:
  - better error handling suggested by Namhyung Kim.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1386076182-14484-9-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index b1d5376..bae8756 100644 (file)
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -6,6 +6,8 @@
 #endif
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <errno.h>
 #include <linux/kernel.h>
 
 /*
@@ -433,3 +435,50 @@ int filename__read_int(const char *filename, int *value)
        close(fd);
        return err;
 }
+
+int filename__read_str(const char *filename, char **buf, size_t *sizep)
+{
+       size_t size = 0, alloc_size = 0;
+       void *bf = NULL, *nbf;
+       int fd, n, err = 0;
+
+       fd = open(filename, O_RDONLY);
+       if (fd < 0)
+               return -errno;
+
+       do {
+               if (size == alloc_size) {
+                       alloc_size += BUFSIZ;
+                       nbf = realloc(bf, alloc_size);
+                       if (!nbf) {
+                               err = -ENOMEM;
+                               break;
+                       }
+
+                       bf = nbf;
+               }
+
+               n = read(fd, bf + size, alloc_size - size);
+               if (n < 0) {
+                       if (size) {
+                               pr_warning("read failed %d: %s\n",
+                                          errno, strerror(errno));
+                               err = 0;
+                       } else
+                               err = -errno;
+
+                       break;
+               }
+
+               size += n;
+       } while (n > 0);
+
+       if (!err) {
+               *sizep = size;
+               *buf   = bf;
+       } else
+               free(bf);
+
+       close(fd);
+       return err;
+}

diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index ce0f73d..adb39f2 100644 (file)
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -308,4 +308,5 @@ char *get_srcline(struct dso *dso, unsigned long addr);
 void free_srcline(char *srcline);
 
 int filename__read_int(const char *filename, int *value);
+int filename__read_str(const char *filename, char **buf, size_t *sizep);
 #endif /* GIT_COMPAT_UTIL_H */