non-busybox dhcp clients (was: PATCH: ifupdown.c, udhcpc, and standalone shell)

[Gabriel L. Somlo]

On Thu, Oct 05, 2006 at 01:08:52PM -0400, Rob Landley wrote:
> I generally just called execvp() or some such and if I got control back, that 
> wasn't it.

OK, so this patch adds a do_which() function to libbb. I'll send
another email which replaces my previous ifupdown patch with one that
uses do_which(). What still needs to be done if these are accepted is
to replace debianutils/which.c with a call to do_which(), but I'll
hold on that until I get feedback on this stuff first...

Thanks,
Gabriel


diff -NarU5 busybox-svn-16294/include/libbb.h busybox-svn-16294.which/include/libbb.h
--- busybox-svn-16294/include/libbb.h	2006-10-03 13:01:09.000000000 -0400
+++ busybox-svn-16294.which/include/libbb.h	2006-10-05 14:08:25.000000000 -0400
@@ -337,10 +337,12 @@
 char *concat_subpath_file(const char *path, const char *filename);
 char *last_char_is(const char *s, int c);
 
 char *fgets_str(FILE *file, const char *terminating_string);
 
+char *do_which(char *program);
+
 extern USE_DESKTOP(long long) int uncompress(int fd_in, int fd_out);
 extern int inflate(int in, int out);
 
 extern struct hostent *xgethostbyname(const char *name);
 extern struct hostent *xgethostbyname2(const char *name, int af);
diff -NarU5 busybox-svn-16294/libbb/do_which.c busybox-svn-16294.which/libbb/do_which.c
--- busybox-svn-16294/libbb/do_which.c	1969-12-31 19:00:00.000000000 -0500
+++ busybox-svn-16294.which/libbb/do_which.c	2006-10-05 14:09:14.000000000 -0400
@@ -0,0 +1,30 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) 2006 Gabriel L. Somlo
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+/* search PATH for executable filename; return full path if found and executable
+ * return NULL otherwise
+*/
+
+#include "libbb.h"
+
+char *do_which(char *program)
+{
+    struct stat buf;
+    char *p, *path = xstrdup(getenv("PATH"));
+    char *ret = NULL;
+    for (p = strtok(path, ":"); p; p = strtok(NULL, ":")) {
+        ret = concat_path_file(p, program);
+        if ((stat(ret, &buf) == 0) &&
+			S_ISREG(buf.st_mode) && (S_IXUSR & buf.st_mode)) break;
+        free(ret);
+        ret = NULL;
+    }
+    free(path);
+    return ret;
+}
diff -NarU5 busybox-svn-16294/libbb/Makefile.in busybox-svn-16294.which/libbb/Makefile.in
--- busybox-svn-16294/libbb/Makefile.in	2006-10-03 13:01:07.000000000 -0400
+++ busybox-svn-16294.which/libbb/Makefile.in	2006-10-05 14:08:50.000000000 -0400
@@ -31,11 +31,11 @@
 	xgethostbyname.c xgethostbyname2.c xreadlink.c xgetlarg.c \
 	fclose_nonstdin.c fflush_stdout_and_exit.c \
 	getopt_ulflags.c default_error_retval.c wfopen_input.c speed_table.c \
 	perror_nomsg_and_die.c perror_nomsg.c skip_whitespace.c bb_askpass.c \
 	warn_ignoring_args.c concat_subpath_file.c vfork_daemon_rexec.c \
-	bb_do_delay.c
+	bb_do_delay.c do_which.c
 
 # conditionally compiled objects:
 LIBBB-$(CONFIG_FEATURE_MOUNT_LOOP)+= loop.c
 LIBBB-$(CONFIG_LOSETUP)+= loop.c
 LIBBB-$(CONFIG_FEATURE_MTAB_SUPPORT)+= mtab.c