initial implementation

1 files changed, 275 insertions, 0 deletions

diff --git a/printf.c b/printf.c
new file mode 100644
index 0000000..ec0b351
--- /dev/null
+++ b/printf.c
@@ -0,0 +1,275 @@
+#define _XOPEN_SOURCE 700
+#include <errno.h>
+#include <ctype.h>
+#include <locale.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static int errors = 0;
+
+static void diagnose(const char *fmt, ...)
+{
+	char ofmt[strlen(fmt) + 10];
+	sprintf(ofmt, "printf: %s\n", fmt);
+
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, ofmt, ap);
+	va_end(ap);
+
+	errors = 1;
+}
+
+static const char *escape(const char *esc)
+{
+	if (isdigit(*esc)) {
+		char oct[4] = {0};
+		oct[0] = *esc++;
+		if (isdigit(*esc)) {
+			oct[1] = *esc++;
+		}
+		if (isdigit(*esc)) {
+			oct[2] = *esc++;
+		}
+
+		putchar(strtol(oct, NULL, 8));
+		return esc;
+	}
+
+	switch (*esc) {
+	case '\\':
+		putchar('\\');
+		break;
+
+	case 'a':
+		putchar('\a');
+		break;
+
+	case 'b':
+		putchar('\b');
+		break;
+
+	case 'f':
+		putchar('\f');
+		break;
+
+	case 'n':
+		putchar('\n');
+		break;
+
+	case 'r':
+		putchar('\r');
+		break;
+
+	case 't':
+		putchar('\t');
+		break;
+
+	case 'v':
+		putchar('\v');
+		break;
+
+	default:
+		diagnose("unknown escape \"\\%c\"", *esc);
+		break;
+	}
+	return esc + 1;
+}
+
+static const char *echo(const char *s)
+{
+	while (*s) {
+		if (*s != '\\') {
+			putchar(*s++);
+			continue;
+		}
+
+		s++;
+		if (*s == 'c') {
+			return NULL;
+		}
+
+		if (*s == '0' || !isdigit(*s)) {
+			s = escape(s);
+		} else {
+			diagnose("unknown escape \"\\%c\"", *s);
+			s++;
+		}
+	}
+	return s;
+}
+
+static const char *convert(const char *conv, const char *operand)
+{
+	double d;
+	long long int i;
+	unsigned long long int u;
+	char *end = NULL;
+	char oconv[strlen(conv) + 11];
+	char *ocend = oconv;
+	char fconv[10];
+
+	memset(oconv, 0, sizeof(oconv));
+	strcpy(oconv, "%");
+	ocend++;
+
+	/* flags */
+	while (strspn(conv, "-+ #0")) {
+		*ocend++ = *conv++;
+	}
+
+	/* width */
+	while (isdigit(*conv)) {
+		*ocend++ = *conv++;
+	}
+
+	/* precision */
+	if (*conv == '.') {
+		*ocend++ = *conv++;
+		while (isdigit(*conv)) {
+			*ocend++ = *conv++;
+		}
+	}
+
+	/* conversion specifier */
+	switch (*conv) {
+	case 'b':
+		return echo(operand);
+
+	case 's':
+		strcat(oconv, "s");
+		printf(oconv, operand);
+		break;
+
+	case 'c':
+		strcat(oconv, "c");
+		printf(oconv, *operand);
+		break;
+
+	case 'a':
+	case 'A':
+	case 'e':
+	case 'E':
+	case 'f':
+	case 'F':
+	case 'g':
+	case 'G':
+		errno = 0;
+		d = strtod(operand, &end);
+		if (errno != 0) {
+			diagnose("overflow converting \"%s\"", operand);
+		}
+		if (*end != '\0') {
+			diagnose("\"%s\" not completely converted", operand);
+		}
+		sprintf(fconv, "%c", *conv);
+		strcat(oconv, fconv);
+		printf(oconv, d);
+		break;
+
+	case 'd':
+	case 'i':
+		errno = 0;
+		if (*operand == '\'' || *operand == '"') {
+			i = operand[1];
+		} else {
+			i = strtoll(operand, &end, 0);
+			if (*end != '\0') {
+				diagnose("\"%s\" not completely converted", operand);
+			}
+		}
+
+		if (errno != 0) {
+			diagnose("overflow converting \"%s\"", operand);
+		}
+
+		sprintf(fconv, "ll%c", *conv);
+		strcat(oconv, fconv);
+		printf(oconv, i);
+		break;
+
+	case 'o':
+	case 'u':
+	case 'x':
+	case 'X':
+		errno = 0;
+		if (*operand == '\'' || *operand == '"') {
+			u = operand[1];
+		} else {
+			u = strtoull(operand, &end, 0);
+			if (errno != 0) {
+				diagnose("overflow converting \"%s\"", operand);
+			}
+		}
+
+		if (*end != '\0') {
+			diagnose("\"%s\" not completely converted", operand);
+		}
+
+		sprintf(fconv, "ll%c", *conv);
+		strcat(oconv, fconv);
+		printf(oconv, u);
+		break;
+
+	default:
+		diagnose("invalid conversion specifier '%c'", *conv);
+		return conv;
+	}
+
+	return conv + 1;
+}
+
+int main(int argc, char *argv[])
+{
+	setlocale(LC_ALL, "");
+
+	while (getopt(argc, argv, "") != -1) {
+		return 1;
+	}
+
+	int formatind = optind++;
+	const char *format = argv[formatind];
+	const char *operand = argv[optind++];
+
+	int counting = 1;
+	int count = 0;
+	do {
+		while (*format) {
+			if (*format == '%') {
+				if (*(format + 1) == '%') {
+					putchar('%');
+					format += 2;
+				} else {
+					if (counting) {
+						count++;
+					}
+					format = convert(format + 1, operand);
+					if (operand) {
+						operand = argv[optind++];
+					}
+				}
+			} else if (*format == '\\') {
+				format = escape(format + 1);
+			} else {
+				putchar(*format);
+				format++;
+			}
+
+			if (format == NULL) {
+				break;
+			}
+		}
+
+		if (count == 0) {
+			break;
+		}
+
+		format = argv[formatind];
+		counting = 0;
+	} while (operand);
+
+	return errors;
+}