LibC: Implement various things to get GNU bc building and running.

Looks like that's all we needed, and bc now runs. :^)

LibC/stdio.cpp

@@ -133,6 +133,11 @@ int getchar()
     return getc(stdin);
 }
 
+int ungetc(int, FILE*)
+{
+    ASSERT_NOT_REACHED();
+}
+
 int fputc(int ch, FILE* stream)
 {
     assert(stream);

LibC/stdio.h

@@ -40,6 +40,7 @@ int fileno(FILE*);
 int fgetc(FILE*);
 int getc(FILE*);
 int getchar();
+int ungetc(int c, FILE*);
 FILE* fdopen(int fd, const char* mode);
 FILE* fopen(const char* pathname, const char* mode);
 int fclose(FILE*);

LibC/stdlib.cpp

@@ -262,4 +262,9 @@ void srandom(unsigned seed)
     srand(seed);
 }
 
+int system(const char* command)
+{
+    return execl("/bin/sh", "sh", "-c", command, nullptr);
+}
+
 }

LibC/stdlib.h

@@ -21,6 +21,7 @@ void abort() __NORETURN;
 char* ptsname(int fd);
 int ptsname_r(int fd, char* buffer, size_t);
 int abs(int);
+int system(const char* command);
 
 #define RAND_MAX 32767
 int rand();

LibC/string.cpp

@@ -186,6 +186,17 @@ char* strchr(const char* str, int c)
     }
 }
 
+void* memchr(const void* ptr, int c, size_t size)
+{
+    char ch = c;
+    char* cptr = (char*)ptr;
+    for (size_t i = 0; i < size; ++i) {
+        if (cptr[i] == ch)
+            return cptr + i;
+    }
+    return nullptr;
+}
+
 char* strrchr(const char* str, int ch)
 {
     char *last = nullptr;

LibC/string.h

@@ -11,6 +11,7 @@ int strncmp(const char*, const char*, size_t);
 int memcmp(const void*, const void*, size_t);
 void* memcpy(void*, const void*, size_t);
 void* memmove(void*, const void*, size_t);
+void* memchr(const void*, int c, size_t);
 void bzero(void*, size_t);
 void bcopy(const void*, void*, size_t);
 void* memset(void*, int, size_t);

LibC/unistd.cpp

@@ -9,6 +9,7 @@
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <Kernel/Syscall.h>
+#include <AK/Vector.h>
 
 extern "C" {
 
@@ -26,9 +27,28 @@ 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 execl(const char* filename, const char* arg0, ...)
+{
+    Vector<const char*> args;
+    args.append(arg0);
+
+    va_list ap;
+    va_start(ap, arg0);
+    for (;;) {
+        const char* arg = va_arg(ap, const char*);
+        if (!arg)
+            break;
+        args.append(arg);
+    }
+    va_end(ap);
+
+    return execve(filename, (char* const *)args.data(), nullptr);
+}
+
 uid_t getuid()
 {
     return syscall(SC_getuid);

LibC/unistd.h

@@ -13,6 +13,7 @@ inline int getpagesize() { return 4096; }
 pid_t fork();
 int execve(const char* filename, char* const argv[], char* const envp[]);
 int execvp(const char* filename, char* const argv[]);
+int execl(const char* filename, const char* arg, ...);
 void sync();
 void _exit(int status);
 pid_t getsid(pid_t);

Userland/sh.cpp

@@ -358,13 +358,12 @@ static void greeting()
     printf("\n%s/%s on %s\n\n", uts.sysname, uts.machine, g->ttyname);
 }
 
-int main(int, char**)
+int main(int argc, char** argv)
 {
     g = new GlobalState;
     g->uid = getuid();
     g->sid = setsid();
     tcsetpgrp(0, getpgrp());
-
     tcgetattr(0, &g->termios);
 
     {
@@ -391,6 +390,11 @@ int main(int, char**)
         endpwent();
     }
 
+    if (argc > 1 && !strcmp(argv[1], "-c")) {
+        fprintf(stderr, "FIXME: Implement /bin/sh -c\n");
+        return 1;
+    }
+
     greeting();
 
     char linebuf[128];