init

tls/openssl-wasm/src/c_shim/vsnprintf_shim.c

@@ -0,0 +1,223 @@
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+
+typedef enum {
+    LEN_DEFAULT = 0,
+    LEN_HH,
+    LEN_H,
+    LEN_L,
+    LEN_LL,
+    LEN_Z,
+    LEN_T,
+    LEN_J
+} length_mod_t;
+
+static void out_char(char *dst, size_t size, size_t *written, char ch) {
+    if (*written + 1 < size && dst != NULL) {
+        dst[*written] = ch;
+    }
+    *written += 1;
+}
+
+static void out_str(char *dst, size_t size, size_t *written, const char *str) {
+    if (!str) {
+        str = "(null)";
+    }
+    while (*str) {
+        out_char(dst, size, written, *str++);
+    }
+}
+
+static void out_uint(
+    char *dst,
+    size_t size,
+    size_t *written,
+    unsigned long long value,
+    unsigned base,
+    int uppercase
+) {
+    char buf[64];
+    size_t i = 0;
+    const char *digits = uppercase ? "0123456789ABCDEF" : "0123456789abcdef";
+
+    if (base < 2 || base > 16) {
+        return;
+    }
+    if (value == 0) {
+        out_char(dst, size, written, '0');
+        return;
+    }
+    while (value != 0 && i < sizeof(buf)) {
+        buf[i++] = digits[value % base];
+        value /= base;
+    }
+    while (i > 0) {
+        out_char(dst, size, written, buf[--i]);
+    }
+}
+
+static long long read_signed_arg(va_list *ap, length_mod_t len) {
+    switch (len) {
+        case LEN_HH: return (signed char)va_arg(*ap, int);
+        case LEN_H: return (short)va_arg(*ap, int);
+        case LEN_L: return va_arg(*ap, long);
+        case LEN_LL: return va_arg(*ap, long long);
+        case LEN_Z: return (long long)va_arg(*ap, size_t);
+        case LEN_T: return (long long)va_arg(*ap, ptrdiff_t);
+        case LEN_J: return (long long)va_arg(*ap, intmax_t);
+        case LEN_DEFAULT:
+        default:
+            return va_arg(*ap, int);
+    }
+}
+
+static unsigned long long read_unsigned_arg(va_list *ap, length_mod_t len) {
+    switch (len) {
+        case LEN_HH: return (unsigned char)va_arg(*ap, unsigned int);
+        case LEN_H: return (unsigned short)va_arg(*ap, unsigned int);
+        case LEN_L: return va_arg(*ap, unsigned long);
+        case LEN_LL: return va_arg(*ap, unsigned long long);
+        case LEN_Z: return (unsigned long long)va_arg(*ap, size_t);
+        case LEN_T: return (unsigned long long)va_arg(*ap, ptrdiff_t);
+        case LEN_J: return (unsigned long long)va_arg(*ap, uintmax_t);
+        case LEN_DEFAULT:
+        default:
+            return va_arg(*ap, unsigned int);
+    }
+}
+
+int vsnprintf(char *dst, size_t size, const char *format, va_list ap) {
+    size_t written = 0;
+
+    if (!format) {
+        if (dst != NULL && size > 0) {
+            dst[0] = '\0';
+        }
+        return 0;
+    }
+
+    while (*format) {
+        if (*format != '%') {
+            out_char(dst, size, &written, *format++);
+            continue;
+        }
+        format++;
+        if (*format == '%') {
+            out_char(dst, size, &written, '%');
+            format++;
+            continue;
+        }
+
+        while (*format == '-' || *format == '+' || *format == ' ' || *format == '#' || *format == '0') {
+            format++;
+        }
+
+        if (*format == '*') {
+            (void)va_arg(ap, int);
+            format++;
+        } else {
+            while (*format >= '0' && *format <= '9') {
+                format++;
+            }
+        }
+
+        if (*format == '.') {
+            format++;
+            if (*format == '*') {
+                (void)va_arg(ap, int);
+                format++;
+            } else {
+                while (*format >= '0' && *format <= '9') {
+                    format++;
+                }
+            }
+        }
+
+        length_mod_t len = LEN_DEFAULT;
+        if (*format == 'h') {
+            format++;
+            len = (*format == 'h') ? (format++, LEN_HH) : LEN_H;
+        } else if (*format == 'l') {
+            format++;
+            len = (*format == 'l') ? (format++, LEN_LL) : LEN_L;
+        } else if (*format == 'z') {
+            len = LEN_Z;
+            format++;
+        } else if (*format == 't') {
+            len = LEN_T;
+            format++;
+        } else if (*format == 'j') {
+            len = LEN_J;
+            format++;
+        }
+
+        switch (*format) {
+            case 'c': {
+                int ch = va_arg(ap, int);
+                out_char(dst, size, &written, (char)ch);
+                break;
+            }
+            case 's': {
+                const char *str = va_arg(ap, const char *);
+                out_str(dst, size, &written, str);
+                break;
+            }
+            case 'd':
+            case 'i': {
+                long long value = read_signed_arg(&ap, len);
+                unsigned long long mag = (value < 0)
+                    ? (unsigned long long)(-(value + 1)) + 1ULL
+                    : (unsigned long long)value;
+                if (value < 0) {
+                    out_char(dst, size, &written, '-');
+                }
+                out_uint(dst, size, &written, mag, 10, 0);
+                break;
+            }
+            case 'u': {
+                unsigned long long value = read_unsigned_arg(&ap, len);
+                out_uint(dst, size, &written, value, 10, 0);
+                break;
+            }
+            case 'x': {
+                unsigned long long value = read_unsigned_arg(&ap, len);
+                out_uint(dst, size, &written, value, 16, 0);
+                break;
+            }
+            case 'X': {
+                unsigned long long value = read_unsigned_arg(&ap, len);
+                out_uint(dst, size, &written, value, 16, 1);
+                break;
+            }
+            case 'o': {
+                unsigned long long value = read_unsigned_arg(&ap, len);
+                out_uint(dst, size, &written, value, 8, 0);
+                break;
+            }
+            case 'p': {
+                uintptr_t value = (uintptr_t)va_arg(ap, void *);
+                out_str(dst, size, &written, "0x");
+                out_uint(dst, size, &written, (unsigned long long)value, 16, 0);
+                break;
+            }
+            default: {
+                out_char(dst, size, &written, '%');
+                if (*format) {
+                    out_char(dst, size, &written, *format);
+                }
+                break;
+            }
+        }
+
+        if (*format) {
+            format++;
+        }
+    }
+
+    if (dst != NULL && size > 0) {
+        size_t end = (written < size) ? written : (size - 1);
+        dst[end] = '\0';
+    }
+    return (int)written;
+}