m

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 191 insertions, 0 deletions

diff --git a/src/unistd/fexec.c b/src/unistd/fexec.c
new file mode 100644
index 0000000..bf022e4
--- /dev/null
+++ b/src/unistd/fexec.c
@@ -0,0 +1,191 @@
+/**
+ * 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 <stdarg.h>
+#include <errno.h>
+#include <alloca.h>
+#include <string.h>
+#include <stdlib.h>
+
+
+
+/**
+ * The current environment variables.
+ */
+extern char** environ;
+
+
+
+/**
+ * Common code for the `fexecl*` functions.
+ * 
+ * @param   fd          The first argument of said functions.
+ * @param   argv        The rest of the arguments of said functions;
+ *                      may conclude `envp`.
+ * @param   fetch_envp  Whether `argv` includes `envp`.
+ * 
+ * @throws              Any error specified for execve(2).
+ */
+static void vexec(int fd, va_list argv, int fetch_envp)
+{
+  char* const* envp = environ;
+  size_t n = 0, i;
+  va_list args;
+  char** argv_;
+  
+  va_copy(args, argv);
+  while (n++, va_arg(args, char*) != NULL)
+    break;
+  
+  if (fetch_envp)
+    envp = va_arg(args, char* const*);
+  
+  argv_ = alloca(n * sizeof(char*));
+  for (i = 0; i < n; i++)
+    argv_[i] = va_arg(argv, char*);
+  
+  fexecve(fd, argv_, envp);
+}
+
+
+
+/**
+ * Replace the current process image with a new process image.
+ * 
+ * This is a slibc extension.
+ * 
+ * @param   fd   File descriptor for the file to execute.
+ * @param   ...  The arguments with which to execute the file.
+ *               The arguments should have the type `const char*`.
+ *               As a slibc extension, it can be empty.
+ *               This list shall be terminated by a `NULL` sentinel.
+ * @return       This function does not return on success,
+ *               on error, -1 is returned and `errno` is
+ *               set to describe the error.
+ * 
+ * @throws       Any error specified for execve(2).
+ */
+int fexecl(int fd, ... /*, NULL */)
+{
+  int saved_errno;
+  va_list argv;
+  va_start(argv, path);
+  vfexec(fd, argv, 0);
+  saved_errno = errno;
+  va_end(argv);
+  return errno = saved_errno, -1;
+}
+
+
+/**
+ * Replace the current process image with a new process image.
+ * 
+ * This is a slibc extension.
+ * 
+ * @param   fd    File descriptor for the file to execute.
+ * @param   ...   The arguments with which to execute the file.
+ *                The arguments should have the type `const char*`.
+ *                As a slibc extension, it can be empty.
+ *                This list shall be terminated by a `NULL` sentinel.
+ * @param   envp  The list of environment variables the new program shall
+ *                have set. Each element shall be formatted $name=$value.
+ *                This list shall be `NULL`-terminated. The behaviour
+ *                is system-dependant if this argument is `NULL`.
+ * @return        This function does not return on success,
+ *                on error, -1 is returned and `errno` is
+ *                set to describe the error.
+ * 
+ * @throws        Any error specified for execve(2).
+ */
+int fexecle(int fd, ... /*, NULL, char* const envp[] */)
+{
+  int saved_errno;
+  va_list argv;
+  va_start(argv, path);
+  vfexec(fd, argv, 1);
+  saved_errno = errno;
+  va_end(argv);
+  return errno = saved_errno, -1;
+}
+
+
+/**
+ * Replace the current process image with a new process image.
+ * 
+ * This is a slibc extension.
+ * 
+ * @param   fd    File descriptor for the file to execute.
+ * @param   argv  The arguments with which to execute the file.
+ *                This parameter should really have the type
+ *                `const char* const[]`, but that probably not
+ *                so because compiles take issue with casts
+ *                adding const to any pointer in the type
+ *                except the outmost pointer. This list shall
+ *                be `NULL`-terminated. The behaviour is
+ *                system-dependant if this argument is `NULL`.
+ * @return        This function does not return on success,
+ *                on error, -1 is returned and `errno` is
+ *                set to describe the error.
+ * 
+ * @throws        Any error specified for execve(2).
+ */
+int fexecv(int fd, char* const argv[])
+{
+  return fexecve(fd, argv, environ);
+}
+
+
+/**
+ * Replace the current process image with a new process image.
+ * 
+ * @param   fd    File descriptor for the file to execute.
+ * @param   argv  The arguments with which to execute the file.
+ *                This parameter should really have the type
+ *                `const char* const[]`, but that probably not
+ *                so because compiles take issue with casts
+ *                adding const to any pointer in the type
+ *                except the outmost pointer. This list shall
+ *                be `NULL`-terminated. The behaviour is
+ *                system-dependant if this argument is `NULL`.
+ * @param   envp  The list of environment variables the new program shall
+ *                have set. Each element shall be formatted $name=$value.
+ *                This list shall be `NULL`-terminated. The behaviour
+ *                is system-dependant if this argument is `NULL`.
+ * @return        This function does not return on success,
+ *                on error, -1 is returned and `errno` is
+ *                set to describe the error.
+ * 
+ * @throws        Any error specified for execve(2).
+ */
+int fexecve(int fd, char* const argv[], char* const envp[])
+{
+  char pathname[sizeof("/proc/self/fd//") + 3 * sizeof(int)];
+  int saved_errno;
+  
+  sprintf(pathname, "/proc/self/fd/%i/", fd);
+  
+  execve(pathname, argv, envp);
+  saved_errno = errno;
+  
+  if (access("/proc/", X_OK))
+    saved_errno = ENOSYS;
+  
+  errno = saved_errno == ENOENT ? EBADF : saved_errno;
+  return -1;
+}
+