Redo the exec functions to comply with SUSv3.

1 files changed, 319 insertions, 0 deletions

diff --git a/libc/unistd/exec.c b/libc/unistd/exec.c
new file mode 100644
index 000000000..fa1eda2b9
--- /dev/null
+++ b/libc/unistd/exec.c
@@ -0,0 +1,319 @@
+/*  Copyright (C) 2004     Manuel Novoa III
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Library General Public
+ *  License along with this library; if not, write to the Free
+ *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/* Jan 1, 2004
+ *   Initial version of a SUSv3 compliant exec*() functions.
+ */
+
+/* NOTE: Strictly speaking, there could be problems from accessing
+ * __environ in multithreaded programs.  The only way around this
+ * that I see is to essentially lock __environ access (modifying
+ * the setenv code), make a copy of the environment table (just the
+ * pointers since the strings themselves are never freed), and then
+ * unlock prior to the execve call.  If that fails, then we'd need
+ * to free the storage allocated for the copy.  Better ideas anyone?
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <limits.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+extern char *__strchrnul(const char *s, int c);
+
+/**********************************************************************/
+#ifdef __UCLIBC_HAS_MMU__
+
+/* We have an MMU, so use alloca() to grab space for buffers and
+ * arg lists. */
+
+# define EXEC_ALLOC_SIZE(VAR)	/* nothing to do */
+# define EXEC_ALLOC(SIZE,VAR)	alloca((SIZE))
+# define EXEC_FREE(PTR,VAR)		((void)0)
+
+#else
+
+/* We do not have an MMU, so using alloca() is not an option.
+ * Less obviously, using malloc() is not an option either since
+ * malloc()ed memory can leak in a vfork() and exec*() situation.
+ * Therefore, we must use mmap() and unmap() directly.
+ */
+
+# define EXEC_ALLOC_SIZE(VAR)	size_t VAR;	/* Semicolon included! */
+# define EXEC_ALLOC(SIZE,VAR)	__exec_alloc((VAR = (SIZE)))
+# define EXEC_FREE(PTR,VAR)		__exec_free((PTR),(VAR))
+
+extern void *__exec_alloc(size_t size);
+extern void __exec_free(void *ptr, size_t size);
+
+#endif
+/**********************************************************************/
+#ifdef L___exec_alloc
+
+#ifndef __UCLIBC_HAS_MMU__
+
+void *__exec_alloc(size_t size)
+{
+	void *p;
+
+	p = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
+
+	return (p != MAP_FAILED) ? p : NULL;
+}
+
+void __exec_free(void *ptr, size_t size)
+{
+	if (ptr) {
+		munmap(ptr, size);
+	}
+}
+
+#endif
+
+#endif
+/**********************************************************************/
+#ifdef L_execl
+
+int execl(const char *path, const char *arg, ...)
+{
+	EXEC_ALLOC_SIZE(size)		/* Do NOT add a semicolon! */
+	int n;
+	char **argv;
+	char **p;
+	va_list args;
+	
+	n = 0;
+	va_start(args, arg);
+	do {
+		++n;
+	} while (va_arg(args, char *));
+	va_end(args);
+
+	p = argv = (char **) EXEC_ALLOC((n+1) * sizeof(char *), size);
+
+	p[0] = (char *)arg;
+
+	va_start(args, arg);
+	do {
+		*++p = va_arg(args, char *);
+	} while (--n);
+	va_end(args);
+
+	n = execve(path, (char *const *) argv, __environ);
+
+	EXEC_FREE(argv, size);
+
+	return n;
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execv
+
+int execv(__const char *path, char *__const argv[])
+{
+	return execve(path, argv, __environ);
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execle
+
+int execle(const char *path, const char *arg, ...)
+{
+	EXEC_ALLOC_SIZE(size)		/* Do NOT add a semicolon! */
+	int n;
+	char **argv;
+	char **p;
+	char *const *envp;
+	va_list args;
+	
+	n = 0;
+	va_start(args, arg);
+	do {
+		++n;
+	} while (va_arg(args, char *));
+	envp = va_arg(args, char *const *);	/* Varies from execl and execlp. */
+	va_end(args);
+
+	p = argv = (char **) EXEC_ALLOC((n+1) * sizeof(char *), size);
+
+	p[0] = (char *)arg;
+
+	va_start(args, arg);
+	do {
+		*++p = va_arg(args, char *);
+	} while (--n);
+	va_end(args);
+
+	n = execve(path, (char *const *) argv, envp);
+
+	EXEC_FREE(argv, size);
+
+	return n;
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execlp
+
+int execlp(const char *file, const char *arg, ...)
+{
+	EXEC_ALLOC_SIZE(size)		/* Do NOT add a semicolon! */
+	int n;
+	char **argv;
+	char **p;
+	va_list args;
+	
+	n = 0;
+	va_start(args, arg);
+	do {
+		++n;
+	} while (va_arg(args, char *));
+	va_end(args);
+
+	p = argv = (char **) EXEC_ALLOC((n+1) * sizeof(char *), size);
+
+	p[0] = (char *)arg;
+
+	va_start(args, arg);
+	do {
+		*++p = va_arg(args, char *);
+	} while (--n);
+	va_end(args);
+
+	n = execvp(file, (char *const *) argv);
+
+	EXEC_FREE(argv, size);
+
+	return n;
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execvp
+
+/* Use a default path that matches glibc behavior, since SUSv3 says
+ * this is implementation-defined.  The default is current working dir,
+ * /bin, and then /usr/bin. */
+static const char default_path[] = ":/bin:/usr/bin";
+
+int execvp(const char *path, char *const argv[])
+{
+	char *buf = NULL;
+	char *p;
+	char *e;
+	char *s0;
+	char *s;
+	EXEC_ALLOC_SIZE(size = 0)	/* Do NOT add a semicolon! */
+	size_t len;
+	size_t plen;
+
+	if (!path || !*path) {		/* Comply with SUSv3. */
+	BAD:
+		__set_errno(ENOENT);
+		return -1;
+	}
+
+	if (strchr(path, '/')) {
+		execve(path, argv, __environ);
+	CHECK_ENOEXEC:
+		if (errno == ENOEXEC) {
+			char **nargv;
+			EXEC_ALLOC_SIZE(size2) /* Do NOT add a semicolon! */
+			size_t n;
+			/* Need the dimension - 1.  We omit counting the trailing
+			 * NULL but we actually omit the first entry. */
+			for (n=0 ; argv[n] ; n++) {}
+			nargv = (char **) EXEC_ALLOC((n+2) * sizeof(char *), size2);
+			nargv[0] = argv[0];
+			nargv[1] = (char *)path;
+			memcpy(nargv+2, argv+1, n*sizeof(char *));
+			execve("/bin/sh", nargv, __environ);
+			EXEC_FREE(nargv, size2);
+		}
+	} else {
+		if ((p = getenv("PATH")) != NULL) {
+			if (!*p) {
+				goto BAD;
+			}
+		} else {
+			p = (char *) default_path;
+		}
+
+		plen = strlen(path);
+		if (plen > (FILENAME_MAX - 1)) {
+		ALL_TOO_LONG:
+			__set_errno(ENAMETOOLONG);
+			return -1;
+		}
+		len = (FILENAME_MAX - 1) - plen;
+
+		if ((buf = EXEC_ALLOC(FILENAME_MAX, size)) != NULL) {
+			int seen_small = 0;
+			s0 = buf + len;
+			memcpy(s0, path, plen+1);
+
+			do {
+				s = s0;
+				e = __strchrnul(p, ':');
+				if (e > p) {
+					plen = e - p;
+					if (e[-1] != '/') {
+						++plen;
+					}
+					if (plen > len) {
+						goto NEXT;
+					}
+					s -= plen;
+					memcpy(s, p, plen);
+					s[plen-1] = '/';
+				}
+
+				execve(s, argv, __environ);
+
+				seen_small = 1;
+
+				if (errno != ENOENT) {
+					path = s;
+					goto CHECK_ENOEXEC;
+				}
+
+			NEXT:
+				if (!*e) {
+					if (!seen_small) {
+						goto ALL_TOO_LONG;
+					}
+					break;
+				}
+				p = e + 1;
+			} while (1);
+		}
+	}
+
+	EXEC_FREE(buf, size);
+
+	return -1;
+}
+
+#endif
+/**********************************************************************/