From c0a855b36e9872c46d3e89471245923266b68c08 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@member.fsf.org>
Date: Sun, 20 Dec 2015 18:33:52 +0100
Subject: add searchpath and searchpath2
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit
Signed-off-by: Mattias Andrée <maandree@member.fsf.org>
---
include/unistd.h | 74 ++++++++++++++++++++++++++
src/unistd/exec.c | 50 ++----------------
src/unistd/searchpath.c | 55 ++++++++++++++++++++
src/unistd/searchpath2.c | 132 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 264 insertions(+), 47 deletions(-)
create mode 100644 src/unistd/searchpath.c
create mode 100644 src/unistd/searchpath2.c
diff --git a/include/unistd.h b/include/unistd.h
index 47db049..d27f342 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -800,6 +800,80 @@ int fexecv(int, char* const[]);
*/
int fexecve(int, char* const[], char* const[]);
+#if defined(__PLAN9_SOURCE) || defined(__SLIBC_SOURCE)
+/**
+ * Search the environment variable $PATH for an executable
+ * file whose name is the specified name. Slashes are ignored
+ * and treated as any other character. $PATH is searched
+ * for left to right, and ':' is used as the path-delimiter.
+ *
+ * $PATH is not inspected if `name` starts with './', '../', or '/'.
+ *
+ * This is a Plan 9 from Bell Labs compliant slibc extension.
+ *
+ * @etymology (Search) ($PATH) for an executable.
+ *
+ * @param name The name of the sought executable. Must not be `NULL`.
+ * @return The pathname of the sought file, `NULL` on error,
+ * or if not found. Files that are not executable
+ * are (almost) ignored.
+ *
+ * @throws ENOMEM The process cannot allocate enough memory.
+ * @throws ENOENT $PATH is not defined, there are no directories
+ * listed in $PATH, or the sought file is not
+ * exist inside $PATH.
+ * @throws EACCES None of the candidates (with at least one candidate)
+ * are executable by the current user.
+ * @throws Any exception defined for access(3), except for `EROFS`,
+ * these when encountered, the search is aborted, unless
+ * the error is `ENOENT` or `EACCES`.
+ *
+ * @since Always.
+ */
+char* searchpath(const char*);
+#endif
+
+#if defined(__SLIBC_SOURCE)
+/**
+ * Search the environment variable $PATH for an executable
+ * file whose name is the specified name. Slashes are ignored
+ * and treated as any other character. $PATH is searched
+ * for left to right, and ':' is used as the path-delimiter.
+ * If $PATH is not defined, a fallback value for $PATH will be
+ * used.
+ *
+ * $PATH is not inspected if `name` starts with './', '../', or '/'.
+ *
+ * This function was added because it was useful in implementing
+ * the `exec`-function family.
+ *
+ * This is a slibc extension.
+ *
+ * @etymology Variant of (searchpath) that takes (2) arguments.
+ *
+ * @param name The name of the sought executable. Must not be `NULL`.
+ * @param fallback Value to use instead of the value of $PATH, if
+ * path is not defined. If `NULL` the fall rules for
+ * the `exec`-functions are used: The current working
+ * directory, and the default value for $PATH.
+ * @return The pathname of the sought file, `NULL` on error,
+ * or if not found. Files that are not executable
+ * are (almost) ignored.
+ *
+ * @throws ENOMEM The process cannot allocate enough memory.
+ * @throws ENOENT There are no directories listed in $PATH, or
+ * the sought file is not exist inside $PATH.
+ * @throws EACCES None of the candidates (with at least one candidate)
+ * are executable by the current user.
+ * @throws Any exception defined for access(3), except for `EROFS`,
+ * these when encountered, the search is aborted, unless
+ * the error is `ENOENT` or `EACCES`.
+ *
+ * @since Always.
+ */
+char* searchpath2(const char*, const char*);
+#endif
+
#endif
diff --git a/src/unistd/exec.c b/src/unistd/exec.c
index c6e4fca..9375baa 100644
--- a/src/unistd/exec.c
+++ b/src/unistd/exec.c
@@ -21,9 +21,6 @@
#include <alloca.h>
#include <string.h>
#include <stdlib.h>
-/* TODO temporary contants from other headers { */
-#define _CS_PATH 1
-/* } */
@@ -323,12 +320,7 @@ int execve(const char* path, char* const argv[], char* const envp[])
*/
int execvpe(const char* file, char* const argv[], char* const envp[])
{
- char* path = NULL;
char* pathname = NULL;
- char* p;
- char* q;
- size_t len = 0;
- int eacces = 0;
int saved_errno;
if (strchr(file, '/'))
@@ -337,49 +329,13 @@ int execvpe(const char* file, char* const argv[], char* const envp[])
if (!*file)
return errno = ENOENT, -1;
- path = getenv("PATH");
- if (path == NULL)
- {
- if ((len = confstr(_CS_PATH, NULL, 0)))
- {
- path = malloc((2 + len) * sizeof(char));
- if (path == NULL)
- goto fail;
- if (!confstr(_CS_PATH, stpcpy(path, ".:"), len))
- free(path), path = NULL;
- }
- if (path == NULL)
- path = strdup(".:/usr/local/bin:/bin:/usr/bin");
- }
- else
- path = strdup(path);
- if (path == NULL)
- goto fail;
-
- pathname = malloc((strlen(path) + strlen(file) + 2) * sizeof(char));
+ pathname = searchpath2(file, NULL);
if (pathname == NULL)
- goto fail;
-
- for (p = path; *p; p = q + 1)
- {
- if (p == (q = strchr(p, ':')))
- continue;
- *q = '\0';
-
- stpcpy(stpcpy(stpcpy(pathname, p), "/"), file);
-
- execve(pathname, argv, envp);
- if (errno == EACCES) eacces = 1;
- else if (errno != ENOENT) goto fail;
- }
+ return -1;
- free(path);
- free(pathname);
- return errno = (eacces ? EACCES : ENOENT), -1;
+ execve(pathname, argv, envp);
- fail:
saved_errno = errno;
- free(path);
free(pathname);
errno = saved_errno;
return -1;
diff --git a/src/unistd/searchpath.c b/src/unistd/searchpath.c
new file mode 100644
index 0000000..84bc58e
--- /dev/null
+++ b/src/unistd/searchpath.c
@@ -0,0 +1,55 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <unistd.h>
+
+
+
+/**
+ * Search the environment variable $PATH for an executable
+ * file whose name is the specified name. Slashes are ignored
+ * and treated as any other character. $PATH is searched
+ * for left to right, and ':' is used as the path-delimiter.
+ *
+ * $PATH is not inspected if `name` starts with './', '../', or '/'.
+ *
+ * This is a Plan 9 from Bell Labs compliant slibc extension.
+ *
+ * @etymology (Search) ($PATH) for an executable.
+ *
+ * @param name The name of the sought executable.
+ * @return The pathname of the sought file, `NULL` on error,
+ * or if not found. Files that are not executable
+ * are (almost) ignored.
+ *
+ * @throws ENOMEM The process cannot allocate enough memory.
+ * @throws ENOENT $PATH is not defined, there are no directories
+ * listed in $PATH, or the sought file is not
+ * exist inside $PATH.
+ * @throws EACCES None of the candidates (with at least one candidate)
+ * are executable by the current user.
+ * @throws Any exception defined for access(3), except for `EROFS`,
+ * these when encountered, the search is aborted, unless
+ * the error is `ENOENT` or `EACCES`.
+ *
+ * @since Always.
+ */
+char* searchpath(const char* name)
+{
+ return searchpath2(name, "");
+}
+
diff --git a/src/unistd/searchpath2.c b/src/unistd/searchpath2.c
new file mode 100644
index 0000000..9921550
--- /dev/null
+++ b/src/unistd/searchpath2.c
@@ -0,0 +1,132 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+/* TODO temporary contants from other headers { */
+#define _CS_PATH 1
+/* } */
+
+
+
+/**
+ * Search the environment variable $PATH for an executable
+ * file whose name is the specified name. Slashes are ignored
+ * and treated as any other character. $PATH is searched
+ * for left to right, and ':' is used as the path-delimiter.
+ * If $PATH is not defined, a fallback value for $PATH will be
+ * used.
+ *
+ * $PATH is not inspected if `name` starts with './', '../', or '/'.
+ *
+ * This function was added because it was useful in implementing
+ * the `exec`-function family.
+ *
+ * This is a slibc extension.
+ *
+ * @etymology Variant of (searchpath) that takes (2) arguments.
+ *
+ * @param name The name of the sought executable. Must not be `NULL`.
+ * @param fallback Value to use instead of the value of $PATH, if
+ * path is not defined. If `NULL` the fall rules for
+ * the `exec`-functions are used: The current working
+ * directory, and the default value for $PATH.
+ * @return The pathname of the sought file, `NULL` on error,
+ * or if not found. Files that are not executable
+ * are (almost) ignored.
+ *
+ * @throws ENOMEM The process cannot allocate enough memory.
+ * @throws ENOENT There are no directories listed in $PATH, or
+ * the sought file is not exist inside $PATH.
+ * @throws EACCES None of the candidates (with at least one candidate)
+ * are executable by the current user.
+ * @throws Any exception defined for access(3), except for `EROFS`,
+ * these when encountered, the search is aborted, unless
+ * the error is `ENOENT` or `EACCES`.
+ *
+ * @since Always.
+ */
+char* searchpath2(const char* name, const char* fallback)
+{
+ char* path;
+ size_t len = 0;
+ char* pathname = NULL;
+ char* p;
+ char* q;
+ int eacces = 0;
+ int saved_errno;
+
+ if (strstarts(name, "./") || strstarts(name, "../") || strstarts(name, "/"))
+ {
+ if (access(name, X_OK) == 0)
+ return strdup(name);
+ return NULL;
+ }
+
+ path = getenv("PATH");
+ if ((path == NULL) && (fallback == NULL))
+ {
+ if ((len = confstr(_CS_PATH, NULL, 0)))
+ {
+ path = malloc((2 + len) * sizeof(char));
+ if (path == NULL)
+ goto fail;
+ if (!confstr(_CS_PATH, stpcpy(path, ".:"), len))
+ free(path), path = NULL;
+ }
+ if (path == NULL)
+ path = strdup(".:/usr/local/bin:/bin:/usr/bin");
+ }
+ else
+ path = strdup(path == NULL ? fallback : path);
+ if (path == NULL)
+ goto fail;
+
+ pathname = malloc((strlen(path) + strlen(name) + 2) * sizeof(char));
+ if (pathname == NULL)
+ goto fail;
+
+ for (p = path; *p; p = q + 1)
+ {
+ if (p == (q = strchr(p, ':')))
+ continue;
+ *q = '\0';
+
+ stpcpy(stpcpy(stpcpy(pathname, p), "/"), name);
+
+ if (access(pathname, X_OK) == 0)
+ {
+ char* truncated = realloc(pathname, (strlen(pathname) + 1) * sizeof(char));
+ return truncated == NULL ? pathname : truncated;
+ }
+ else if (errno == EACCES) eacces = 1;
+ else if (errno != ENOENT) goto fail;
+ }
+
+ free(path);
+ free(pathname);
+ return errno = (eacces ? EACCES : ENOENT), -1;
+
+ fail:
+ saved_errno = errno;
+ free(path);
+ free(pathname);
+ errno = saved_errno;
+ return -1;
+}
+
--
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