From 4e09bca9e34c226b6d7e34b4fa11248405fd988e Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Sun, 22 Oct 2023 19:50:38 +0200
Subject: Move everything into a new repo.

---
 userland/libc/string/sscanf.c | 193 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 193 insertions(+)
 create mode 100644 userland/libc/string/sscanf.c

(limited to 'userland/libc/string/sscanf.c')

diff --git a/userland/libc/string/sscanf.c b/userland/libc/string/sscanf.c
new file mode 100644
index 0000000..28e1ce1
--- /dev/null
+++ b/userland/libc/string/sscanf.c
@@ -0,0 +1,193 @@
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+extern int errno;
+extern int get_value(char c, long base);
+
+long ftnum(FILE *stream, int base, int *error) {
+  char c;
+  long ret_value = 0;
+  *error = 0;
+  // Ignore inital white-space sequence
+  for (;;) {
+    if (EOF == (c = fgetc(stream))) {
+      *error = 1;
+      return 0;
+    }
+
+    if (!isspace(c)) {
+      ungetc(c, stream);
+      break;
+    }
+  }
+  if (c == '\0') {
+    *error = 1;
+    return 0;
+  }
+  if (!isdigit(c)) {
+    *error = 1;
+    return 0;
+  }
+  if (!(2 <= base && 36 >= base)) {
+    *error = 1;
+    return 0;
+  }
+  for (;;) {
+    if (EOF == (c = fgetc(stream)))
+      break;
+    if (c == '\0') {
+      ungetc(c, stream);
+      break;
+    }
+    int val = get_value(c, base);
+    if (-1 == val) {
+      ungetc(c, stream);
+      break;
+    }
+    if (ret_value * base > LONG_MAX - val) {
+      ungetc(c, stream);
+      errno = ERANGE;
+      *error = 1;
+      return 0;
+    }
+    ret_value *= base;
+    ret_value += val;
+  }
+  return ret_value;
+}
+
+int vfscanf(FILE *stream, const char *format, va_list ap) {
+  int rc = 0; // Upon successful completion, these functions shall return the
+              // number of successfully matched and assigned input items
+  int cont = 0;
+  int suppress = 0;
+  for (; *format; format++) {
+    if (*format != '%' && !cont) {
+      char c;
+      if (isspace(*format))
+        continue;
+      if (EOF == (c = fgetc(stream))) {
+        break;
+      }
+      if (*format == c) // TODO: Make sure this is the correct behaviour
+        continue;
+      // TODO: Make sure this is the correct behaviour
+      errno = EINVAL;
+      assert(0);
+      break;
+    }
+
+    if (*format == '%' && !cont) {
+      cont = 1;
+      continue;
+    }
+
+    int is_long = 0;
+    switch (*format) {
+    case 'l':
+      is_long++;
+      assert(is_long < 3);
+      cont = 1;
+      break;
+    case 'i': // Matches an optionally signed integer, whose format is the same
+              // as expected for the subject sequence of strtol() with 0 for the
+              // base argument.
+    case 'd': {
+      // Matches an optionally signed decimal integer, whose format is the
+      // same as expected for the subject sequence of strtol() with the value
+      // 10 for the base argument. In the absence of a size modifier, the
+      // application shall ensure that the corresponding argument is a pointer
+      // to int.
+      int err = 0;
+      int result = ftnum(stream, 10, &err);
+      if (err) {
+        cont = 0;
+        break;
+      }
+      if (!suppress) {
+        if (2 == is_long) {
+          *((long long *)va_arg(ap, long long *)) = result;
+        } else if (1 == is_long) {
+          *((long *)va_arg(ap, long *)) = result;
+        } else {
+          *((int *)va_arg(ap, int *)) = result;
+        }
+        rc++;
+      }
+      assert(0 == err);
+      cont = 0;
+      break;
+    }
+    case 'c': {
+      char result = fgetc(stream);
+      if (!suppress) {
+        *((char *)va_arg(ap, char *)) = result;
+        rc++;
+      }
+      cont = 0;
+      break;
+    }
+    case '*': // Assignment suppression
+      suppress = 1;
+      cont = 1;
+      break;
+    default:
+      printf("vfscanf: Got %c but not supported.\n", *format);
+      assert(0);
+      break;
+    }
+    if (!cont) {
+      suppress = 0;
+    }
+  }
+  return rc;
+}
+
+struct sscanf_cookie {
+  const char *s;
+};
+
+size_t sscanf_read(FILE *f, unsigned char *s, size_t l) {
+  struct sscanf_cookie *c = f->cookie;
+  if (!*(c->s)) {
+    return 0;
+  }
+  size_t r = 0;
+  for (; l && *(c->s); l--, c->s += 1) {
+    *s = *(c->s);
+    s++;
+    r++;
+  }
+  if (!(*(c->s)))
+    f->is_eof = 1;
+  /*
+  memcpy(s, c->s, l);
+  c->s += l;*/
+  return r;
+}
+
+int vsscanf(const char *s, const char *restrict format, va_list ap) {
+  struct sscanf_cookie c = {.s = s};
+  FILE f = {
+      .read = sscanf_read,
+      .cookie = &c,
+      .has_buffered_char = 0,
+      .is_eof = 0,
+      .has_error = 0,
+      .offset_in_file = 0,
+  };
+  return vfscanf(&f, format, ap);
+}
+
+int sscanf(const char *s, const char *restrict format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  int rc = vsscanf(s, format, ap);
+  va_end(ap);
+  return rc;
+}
-- 
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