[PATCH v4] add util/search-path.{c, h} to test for executables in $PATH
Daniel Kahn Gillmor
dkg at fifthhorseman.net
Tue Feb 9 13:52:05 PST 2016
This is a utility function we can use to see whether an executable is
available.
---
util/Makefile.local | 2 +-
util/search-path.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
util/search-path.h | 24 ++++++++++++++++++++++++
3 files changed, 75 insertions(+), 1 deletion(-)
create mode 100644 util/search-path.c
create mode 100644 util/search-path.h
diff --git a/util/Makefile.local b/util/Makefile.local
index 905f237..8b2b91b 100644
--- a/util/Makefile.local
+++ b/util/Makefile.local
@@ -5,7 +5,7 @@ extra_cflags += -I$(srcdir)/$(dir)
libutil_c_srcs := $(dir)/xutil.c $(dir)/error_util.c $(dir)/hex-escape.c \
$(dir)/string-util.c $(dir)/talloc-extra.c $(dir)/zlib-extra.c \
- $(dir)/util.c
+ $(dir)/util.c $(dir)/search-path.c
libutil_modules := $(libutil_c_srcs:.c=.o)
diff --git a/util/search-path.c b/util/search-path.c
new file mode 100644
index 0000000..9da21cb
--- /dev/null
+++ b/util/search-path.c
@@ -0,0 +1,50 @@
+#include "search-path.h"
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+
+notmuch_bool_t
+test_for_executable (const char *exename)
+{
+ char *path = NULL, *save = NULL, *tok;
+ notmuch_bool_t ret = FALSE;
+
+ if (strchr (exename, '/')) {
+ if (0 == access (exename, X_OK))
+ return TRUE;
+ else
+ return FALSE;
+ }
+
+ path = getenv ("PATH");
+ if (path)
+ path = strdup (path);
+ else {
+ size_t n = confstr (_CS_PATH, NULL, 0);
+ path = (char *) malloc (n);
+ if (! path)
+ return FALSE;
+ confstr (_CS_PATH, path, n);
+ }
+
+ tok = strtok_r (path, ":", &save);
+ while (tok) {
+ int dir_fd = open (tok, O_DIRECTORY | O_RDONLY);
+ if (dir_fd != -1) {
+ int access = faccessat (dir_fd, exename, X_OK, 0);
+ close (dir_fd);
+ if (access == 0) {
+ ret = TRUE;
+ break;
+ }
+ }
+ tok = strtok_r (NULL, ":", &save);
+ }
+ if (path)
+ free (path);
+ return ret;
+}
diff --git a/util/search-path.h b/util/search-path.h
new file mode 100644
index 0000000..14c4d14
--- /dev/null
+++ b/util/search-path.h
@@ -0,0 +1,24 @@
+#ifndef _SEARCH_PATH_H
+#define _SEARCH_PATH_H
+
+#include "notmuch.h"
+
+/* can an executable be found with the given name?
+ *
+ * Return TRUE only if we can find something to execute with the
+ * associated name.
+ *
+ * if the name has a '/' in it, we look for it directly with
+ * access(exename, X_OK).
+ *
+ * otherwise, we look for it in $PATH (or in confstr(_CS_PATH), if
+ * $PATH is unset).
+ *
+ * This should match the logic for execvp (as well as matching user
+ * expectations, hopefully).
+ */
+
+notmuch_bool_t
+test_for_executable (const char *exename);
+
+#endif
--
2.7.0
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