From 0c2face7b0756ac5d8523551f20a95716d77b9c5 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Wed, 27 Mar 2019 01:39:13 +0100
Subject: [PATCH] LibC: Add creat(), execvp() resolution, and exec*()
 environment inheritance.

---
 LibC/unistd.cpp | 32 ++++++++++++++++++++++++++++----
 LibC/unistd.h   |  1 +
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/LibC/unistd.cpp b/LibC/unistd.cpp
index 6d820d6646..1c140ab88d 100644
--- a/LibC/unistd.cpp
+++ b/LibC/unistd.cpp
@@ -9,8 +9,10 @@
 #include <stdlib.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
+#include <fcntl.h>
 #include <Kernel/Syscall.h>
 #include <AK/Vector.h>
+#include <AK/AKString.h>
 
 extern "C" {
 
@@ -28,7 +30,7 @@ pid_t fork()
 
 int execv(const char* path, char* const argv[])
 {
-    return execve(path, argv, nullptr);
+    return execve(path, argv, environ);
 }
 
 int execve(const char* filename, char* const argv[], char* const envp[])
@@ -39,8 +41,25 @@ int execve(const char* filename, char* const argv[], char* const envp[])
 
 int execvp(const char* filename, char* const argv[])
 {
-    // FIXME: This should do some sort of shell-like path resolution!
-    return execve(filename, argv, nullptr);
+    int rc = execve(filename, argv, nullptr);
+    if (rc < 0 && errno != ENOENT) {
+        printf("execvp failed on first with %s\n", strerror(errno));
+        return rc;
+    }
+    String path = getenv("PATH");
+    if (path.is_empty())
+        path = "/bin:/usr/bin";
+    auto parts = path.split(':');
+    for (auto& part : parts) {
+        auto candidate = String::format("%s/%s", part.characters(), filename);
+        rc = execve(candidate.characters(), argv, environ);
+        if (rc < 0 && errno != ENOENT) {
+            printf("execvp failed on attempt (%s) with %s\n", candidate.characters(), strerror(errno));
+            return rc;
+        }
+    }
+    errno = ENOENT;
+    return -1;
 }
 
 int execl(const char* filename, const char* arg0, ...)
@@ -58,7 +77,7 @@ int execl(const char* filename, const char* arg0, ...)
     }
     va_end(ap);
     args.append(nullptr);
-    return execve(filename, (char* const *)args.data(), nullptr);
+    return execve(filename, (char* const *)args.data(), environ);
 }
 
 uid_t getuid()
@@ -125,6 +144,11 @@ pid_t getpgrp()
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int creat(const char* path, mode_t mode)
+{
+    return open(path, O_CREAT, mode);
+}
+
 int open(const char* path, int options, ...)
 {
     va_list ap;
diff --git a/LibC/unistd.h b/LibC/unistd.h
index 9114572fdc..b1483bcba0 100644
--- a/LibC/unistd.h
+++ b/LibC/unistd.h
@@ -48,6 +48,7 @@ int setuid(uid_t);
 int setgid(gid_t);
 pid_t tcgetpgrp(int fd);
 int tcsetpgrp(int fd, pid_t pgid);
+int creat(const char* path, mode_t);
 int open(const char* path, int options, ...);
 ssize_t read(int fd, void* buf, size_t count);
 ssize_t write(int fd, const void* buf, size_t count);