Where available, use _NSGetExecutablePath() to make $^X absolute.

In Configure, check whether _NSGetExecutablePath() can be used to find the
absolute pathname of the executable. If so, set usensgetexecutablepath in
config.sh and USE_NSGETEXECUTABLEPATH in config.h. If this is set, then use
this approach in S_set_caret_X() to canonicalise $^X as an absolute
path. This approach works on OS X, and possible on other platforms that
use dyld.

1 files changed, 102 insertions, 0 deletions

diff --git a/Configure b/Configure
index 691bd81964..1f0dbefee4 100755
--- a/Configure
+++ b/Configure
@@ -1229,6 +1229,7 @@ nm_opt=''
 nm_so_opt=''
 runnm=''
 usenm=''
+usensgetexecutablepath=''
 useperlio=''
 usesocks=''
 d_oldpthreads=''
@@ -19462,6 +19463,106 @@ $rm_try
 set usekernprocpathname
 eval $setvar
 
+: Determine if we can use _NSGetExecutablePath to find executing program
+echo " "
+echo "Determining whether we can use _NSGetExecutablePath to find executing program..." >&4
+$cat >try.c <<'EOM'
+/* Intentionally a long probe as I'd like to sanity check that the exact
+   approach is going to work, as thinking it will work, but only having it
+   part working at runtime is worse than not having it.  */
+#include <mach-o/dyld.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/param.h>
+#include <string.h>
+
+int
+main(int argc, char **argv) {
+    char buf[1];
+    uint32_t size = sizeof(buf);
+    int result;
+    char *buffer;
+    char *tidied;
+    char *argv_leaf = strrchr(argv[0], '/');
+    char *tidied_leaf;
+
+    if (!argv_leaf) {
+	fprintf(stderr, "Can't locate / in '%s'\n", argv[0]);
+	return 1;
+    }
+
+    _NSGetExecutablePath(buf, &size);
+    if (size > MAXPATHLEN * MAXPATHLEN) {
+	fprintf(stderr, "_NSGetExecutablePath size %u is too long for a path\n",
+		(unsigned int) size);
+	return 2;
+    }
+
+    buffer = malloc(size);
+    if (!buffer) {
+	perror("malloc");
+	return 3;
+    }
+
+    result = _NSGetExecutablePath(buffer, &size);
+    if (result != 0) {
+	fprintf(stderr, "_NSGetExecutablePath returned %i for a size of %u\n",
+		result, (unsigned int) size);
+	return 4;
+    }
+
+    tidied = realpath(buffer, NULL);
+    if (!tidied) {
+	perror("realpath");
+	return 5;
+    }
+
+    free(buffer);
+
+    if (*tidied != '/') {
+	fprintf(stderr, "Not an absolute path: '%s'\n", tidied);
+	return 6;
+    }
+
+    if (strstr(tidied, "/./")) {
+	fprintf(stderr, "Contains /./: '%s'\n", tidied);
+	return 7;
+    }
+
+    if (strstr(tidied, "/../")) {
+	fprintf(stderr, "Contains /../: '%s'\n", tidied);
+	return 8;
+    }
+
+    tidied_leaf = strrchr(tidied, '/');
+    if (strcmp(tidied_leaf, argv_leaf) != 0) {
+	fprintf(stderr, "Leafnames differ: '%s' vs '%s'\n", argv[0], tidied);
+	return 9;
+    }
+
+    free(tidied);
+
+    return 0;
+}
+EOM
+
+val=$undef
+set try
+if eval $compile_ok; then
+	if $run ./try; then
+		echo "You can use _NSGetExecutablePath to find the executing program." >&4
+		val="$define"
+	else
+		echo "Nope, _NSGetExecutablePath doesn't work here." >&4
+	fi
+else
+	echo "I'm unable to compile the test program." >&4
+	echo "I'll assume no _NSGetExecutablePath here." >&4
+fi
+$rm_try
+set usensgetexecutablepath
+eval $setvar
+
 : Check how to flush
 echo " "
 $cat >&4 <<EOM
@@ -23558,6 +23659,7 @@ usemorebits='$usemorebits'
 usemultiplicity='$usemultiplicity'
 usemymalloc='$usemymalloc'
 usenm='$usenm'
+usensgetexecutablepath='$usensgetexecutablepath'
 useopcode='$useopcode'
 useperlio='$useperlio'
 useposix='$useposix'