1 files changed, 99 insertions, 0 deletions
diff --git a/printf.c b/printf.c
new file mode 100644
index 0000000..1d14e54
--- /dev/null
+++ b/printf.c
@@ -0,0 +1,99 @@
+#include <unistd.h>
+#include <errno.h>
+
+struct mini_buffer { 
+  char *x;
+  unsigned int p, n;
+  int fd;
+};
+
+static char buf_space[512];
+struct mini_buffer b = { buf_space, 0, sizeof(buf_space), 1 };
+
+static void s_write(int fd, char *s, int n) {
+  int w;
+  while (n) {
+    w = write(fd,s,n);  
+    if (w==0) _exit(1);
+    if (w==-1) {
+      if (errno == EINTR) continue;
+      _exit(1);
+    }
+    s += w;
+    n -= w;
+  }
+}
+
+void out_flush() { s_write(b.fd, b.x, b.p); b.p=0; }
+void out_char(char ch) { if (b.p==b.n) out_flush(); b.x[b.p] = ch; b.p++; }
+void outs(char *s) { while (*s) { out_char(*s); ++s; } }
+
+static void bad(char *fmt, char *s) {
+  if (b.fd==1) out_flush(); 
+  b.fd=2;
+  outs("\nbad format: "); outs(fmt); outs("\nstart: ");
+  outs(s); outs("\n"); out_flush(); _exit(2);
+}
+
+char *conv_esc(char *x, char *pr_char) {
+  char *e0 = "ntrabfvEe\\";
+  char *e1 = "\n\t\r\a\b\f\v\033\033\\";
+  char ch;
+  int k;
+  for (k=0; k<10; k++)
+    if (e0[k] == *x)
+      { *pr_char = e1[k]; return x; }
+  
+  for (k=0, ch=0; '0'<=*x && *x<'8' && k<3; k++, x++)
+    ch = ch*8 + (*x-'0');
+  if (k == 0) return 0;
+  *pr_char = ch;
+  return --x;
+}
+
+int main(int argc, char **argv) {
+  char *fmt, *s, *x, ch;
+  if (argc<2) _exit(100);
+  fmt = argv[1];
+  argv += 2;
+
+  for (s=fmt; (ch=*s); s++) {
+    if (ch != '%' && ch != '\\') goto print_char;
+    if ((ch = *++s) == 0) goto bad_fmt;
+
+    if (s[-1] == '\\') {
+      if ((x=conv_esc(s,&ch)) == 0) goto bad_fmt;
+      s = x;
+    print_char:
+      out_char(ch);
+    } else {	/* % */
+      switch (ch) {
+      case '%':	goto print_char;
+      case 's':
+      case 'b': 
+	if ((x=*argv++)) { 
+	  if (ch=='s') outs(x);
+	  else {	/* %b */
+	    char *y, *tmp;
+	    for (tmp=x; (ch=*x); x++) {
+	      if (ch == '\\') {
+		if ((y=conv_esc(++x,&ch)) == 0) bad(tmp, x-1);
+		x = y;
+	      }
+	      out_char(ch);
+	    }
+	  }
+	  break;
+	}
+	out_flush(); b.fd=2;
+	outs("\nmissing argument");
+      default:
+	bad_fmt:
+	bad(fmt,s-1);
+      }
+    }
+  }
+  out_flush();
+  fsync(1);
+  _exit(close(1));
+}