Never call qsort on potentially NULL arrays

[elogind.git] / src / shared / fileio.c

diff --git a/src/shared/fileio.c b/src/shared/fileio.c
index 77fd05955a54b4286f4a845025d462d4fbca716f..733b3203880b83bbd8b555de78f0a7c855bea323 100644 (file)
--- a/src/shared/fileio.c
+++ b/src/shared/fileio.c
@@ -24,6 +24,7 @@
 #include "util.h"
 #include "strv.h"
 #include "utf8.h"
+#include "ctype.h"
 
 int write_string_to_file(FILE *f, const char *line) {
         errno = 0;
@@ -648,3 +649,51 @@ int executable_is_script(const char *path, char **interpreter) {
         *interpreter = ans;
         return 1;
 }
+
+/**
+ * Retrieve one field from a file like /proc/self/status.  pattern
+ * should start with '\n' and end with a ':'. Whitespace and zeros
+ * after the ':' will be skipped. field must be freed afterwards.
+ */
+int get_status_field(const char *filename, const char *pattern, char **field) {
+        _cleanup_free_ char *status = NULL;
+        char *t;
+        size_t len;
+        int r;
+
+        assert(filename);
+        assert(pattern);
+        assert(field);
+
+        r = read_full_file(filename, &status, NULL);
+        if (r < 0)
+                return r;
+
+        t = strstr(status, pattern);
+        if (!t)
+                return -ENOENT;
+
+        t += strlen(pattern);
+        if (*t) {
+                t += strspn(t, " \t");
+
+                /* Also skip zeros, because when this is used for
+                 * capabilities, we don't want the zeros. This way the
+                 * same capability set always maps to the same string,
+                 * irrespective of the total capability set size. For
+                 * other numbers it shouldn't matter. */
+                t += strspn(t, "0");
+                /* Back off one char if there's nothing but whitespace
+                   and zeros */
+                if (!*t || isspace(*t))
+                        t --;
+        }
+
+        len = strcspn(t, WHITESPACE);
+
+        *field = strndup(t, len);
+        if (!*field)
+                return -ENOMEM;
+
+        return 0;
+}