5 files changed, 237 insertions, 0 deletions
diff --git a/userland/sh/Makefile b/userland/sh/Makefile
new file mode 100644
index 0000000..adccfb3
--- /dev/null
+++ b/userland/sh/Makefile
@@ -0,0 +1,13 @@
+CC="/home/anton/prj/osdev/sysroot/bin/i686-sb-gcc"
+CFLAGS = -ggdb -ffreestanding -O0 -Wall -Wextra -pedantic -mgeneral-regs-only -Wimplicit-fallthrough -fsanitize=shift,signed-integer-overflow,bounds
+BINS=sh
+all: $(BINS)
+
+sh.o: sh.c
+	$(CC) $(CFLAGS) -L../libc/ -lc -c sh.c -I../libc/
+#	$(CC) $(CFLAGS) ../libc/libc.o ../libc/crt0.o sh.c -I../libc/
+
+clean:
+	rm sh sh.o
+sh: sh.o
+	$(CC) -shared -o sh -ffreestanding -nostdlib $(CFLAGS) sh.o -L../libc/ -lc -lgcc #-L../libc/c.a 
diff --git a/userland/sh/sh b/userland/sh/sh
new file mode 100755
index 0000000..7791495
--- /dev/null
+++ b/userland/sh/sh
diff --git a/userland/sh/sh.c b/userland/sh/sh.c
new file mode 100644
index 0000000..5fe7f63
--- /dev/null
+++ b/userland/sh/sh.c
@@ -0,0 +1,224 @@
+#include <assert.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <poll.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#define MAX_ARGS 20
+
+#define IS_SPECIAL(_c) (';' == _c || '\n' == _c || '&' == _c || '|' == _c)
+
+char *PATH = "/:/bin";
+
+int can_open(char *f) {
+  int rc;
+  if (-1 == (rc = open(f, O_RDONLY, 0)))
+    return 0;
+  close(rc);
+  return 1;
+}
+
+int find_path(char *file, char *buf) {
+  if ('/' == *file || '.' == *file) { // Real path
+    if (!can_open(file)) {
+      return 0;
+    }
+    strcpy(buf, file);
+    return 1;
+  }
+
+  char *p = PATH;
+  for (;;) {
+    char *b = p;
+    for (; *p && ':' != *p; p++)
+      ;
+    size_t l = p - b;
+    strlcpy(buf, b, l);
+    strcat(buf, "/");
+    strcat(buf, file);
+    if (can_open(buf)) {
+      return 1;
+    }
+    if (!*p)
+      break;
+    p++;
+  }
+  return 0;
+}
+
+int internal_exec(char *file, char **argv) {
+  char r_path[PATH_MAX];
+  if (!find_path(file, r_path))
+    return 0;
+  if (-1 == execv(r_path, argv)) {
+    perror("exec");
+    return 0;
+  }
+  return 1;
+}
+
+int execute_program(char *s, size_t l, int ignore_rc, int f_stdout,
+                    int *new_out) {
+  if (!l)
+    return -1;
+
+  char c[l + 1];
+  memcpy(c, s, l);
+  c[l] = 0;
+
+  char *argv[MAX_ARGS];
+  int args = 0;
+  char *p = c;
+  for (size_t i = 0; i <= l; i++) {
+    if (' ' == c[i]) {
+      if (p == c + i) {
+        for (; ' ' == *p; p++, i++)
+          ;
+        i--;
+        continue;
+      }
+      c[i] = '\0';
+
+      if (strlen(p) == 0)
+        break;
+
+      argv[args] = p;
+      args++;
+      p = c + i + 1;
+    } else if (i == l) {
+      if (strlen(p) == 0)
+        break;
+      argv[args] = p;
+      args++;
+    }
+  }
+  argv[args] = NULL;
+
+  int fd[2];
+  pipe(fd);
+
+  int pid = fork();
+  if (0 == pid) {
+    if (new_out)
+      dup2(fd[1], 1);
+    if (-1 != f_stdout)
+      dup2(f_stdout, 0);
+    close(fd[0]);
+    if (!internal_exec(argv[0], argv)) {
+      printf("exec failed\n");
+      exit(1);
+    }
+  }
+
+  close(fd[1]);
+  if (new_out)
+    *new_out = fd[0];
+
+  if (ignore_rc)
+    return 0;
+
+  int rc;
+  wait(&rc);
+  return rc;
+}
+
+int compute_expression(char *exp) {
+  char *n = exp;
+  int ignore_next = 0;
+  int rc;
+  int f_stdout = -1;
+  int new_out = f_stdout;
+  for (; *exp; exp++) {
+    if (!IS_SPECIAL(*exp)) {
+      continue;
+    }
+    if ('\n' == *exp)
+      break;
+    if (';' == *exp) {
+      if (!ignore_next) {
+        execute_program(n, exp - n, 0, f_stdout, NULL);
+      }
+      n = exp + 1;
+      continue;
+    }
+    if ('&' == *exp && '&' == *(exp + 1)) {
+      if (!ignore_next) {
+        rc = execute_program(n, exp - n, 0, f_stdout, NULL);
+        if (0 != rc)
+          ignore_next = 1;
+      }
+      n = exp + 2;
+      exp++;
+      continue;
+    } else if ('&' == *exp) {
+      if (!ignore_next) {
+        execute_program(n, exp - n, 1, f_stdout, NULL);
+      }
+      n = exp + 1;
+      continue;
+    }
+    if ('|' == *exp && '|' == *(exp + 1)) {
+      if (!ignore_next) {
+        rc = execute_program(n, exp - n, 0, f_stdout, NULL);
+        if (0 == rc)
+          ignore_next = 1;
+      }
+      n = exp + 2;
+      exp++;
+      continue;
+    } else if ('|' == *exp) {
+      if (!ignore_next) {
+        execute_program(n, exp - n, 1, f_stdout, &new_out);
+        f_stdout = new_out;
+      }
+      n = exp + 1;
+      continue;
+    }
+  }
+  if (!ignore_next)
+    rc = execute_program(n, exp - n, 0, f_stdout, NULL);
+  return rc;
+}
+
+char *get_line(void) {
+  char *str = malloc(1024);
+  char *p = str;
+  int rc;
+  for (;;) {
+    if (0 == (rc = read(0, p, 1))) {
+      continue;
+    }
+    if (0 > rc) {
+      perror("read");
+      continue;
+    }
+    if (8 == *p) {
+      if (p == str)
+        continue;
+      putchar(*p);
+      p--;
+      continue;
+    }
+    putchar(*p);
+    if ('\n' == *p) {
+      break;
+    }
+    p++;
+  }
+  p++;
+  *p = '\0';
+  return str;
+}
+
+int main(void) {
+  for (;;) {
+    printf("/ : ");
+    char *l = get_line();
+    compute_expression(l);
+    free(l);
+  }
+  return 0;
+}
diff --git a/userland/sh/sh_a b/userland/sh/sh_a
new file mode 100755
index 0000000..7b435ab
--- /dev/null
+++ b/userland/sh/sh_a
diff --git a/userland/sh/sh_bad b/userland/sh/sh_bad
new file mode 100755
index 0000000..7f93418
--- /dev/null
+++ b/userland/sh/sh_bad