printfmt.c
#include <defs.h>
#include <x86.h>
#include <error.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
/* *
* Space or zero padding and a field width are supported for the numeric
* formats only.
*
* The special format %e takes an integer error code
* and prints a string describing the error.
* The integer may be positive or negative,
* so that -E_NO_MEM and E_NO_MEM are equivalent.
* */
static const char * const error_string[MAXERROR + 1] = {
[0] NULL,
[E_UNSPECIFIED] "unspecified error",
[E_BAD_PROC] "bad process",
[E_INVAL] "invalid parameter",
[E_NO_MEM] "out of memory",
[E_NO_FREE_PROC] "out of processes",
[E_FAULT] "segmentation fault",
[E_INVAL_ELF] "invalid elf file",
[E_KILLED] "process is killed",
[E_PANIC] "panic failure",
[E_NO_DEV] "no such device",
[E_NA_DEV] "device not available",
[E_BUSY] "device/file is busy",
[E_NOENT] "no such file or directory",
[E_ISDIR] "is a directory",
[E_NOTDIR] "not a directory",
[E_XDEV] "cross device link",
[E_UNIMP] "unimplemented feature",
[E_SEEK] "illegal seek",
[E_MAX_OPEN] "too many files are open",
[E_EXISTS] "file or directory already exists",
[E_NOTEMPTY] "directory is not empty",
};
/* *
* printnum - print a number (base <= 16) in reverse order
* @putch: specified putch function, print a single character
* @fd: file descriptor
* @putdat: used by @putch function
* @num: the number will be printed
* @base: base for print, must be in [1, 16]
* @width: maximum number of digits, if the actual width is less than @width, use @padc instead
* @padc: character that padded on the left if the actual width is less than @width
* */
static void
printnum(void (*putch)(int, void*, int), int fd, void *putdat,
unsigned long long num, unsigned base, int width, int padc) {
unsigned long long result = num;
unsigned mod = do_div(result, base);
// first recursively print all preceding (more significant) digits
if (num >= base) {
printnum(putch, fd, putdat, result, base, width - 1, padc);
} else {
// print any needed pad characters before first digit
while (-- width > 0)
putch(padc, putdat, fd);
}
// then print this (the least significant) digit
putch("0123456789abcdef"[mod], putdat, fd);
}
/* *
* getuint - get an unsigned int of various possible sizes from a varargs list
* @ap: a varargs list pointer
* @lflag: determines the size of the vararg that @ap points to
* */
static unsigned long long
getuint(va_list *ap, int lflag) {
if (lflag >= 2) {
return va_arg(*ap, unsigned long long);
}
else if (lflag) {
return va_arg(*ap, unsigned long);
}
else {
return va_arg(*ap, unsigned int);
}
}
/* *
* getint - same as getuint but signed, we can't use getuint because of sign extension
* @ap: a varargs list pointer
* @lflag: determines the size of the vararg that @ap points to
* */
static long long
getint(va_list *ap, int lflag) {
if (lflag >= 2) {
return va_arg(*ap, long long);
}
else if (lflag) {
return va_arg(*ap, long);
}
else {
return va_arg(*ap, int);
}
}
/* *
* printfmt - format a string and print it by using putch
* @putch: specified putch function, print a single character
* @fd: file descriptor
* @putdat: used by @putch function
* @fmt: the format string to use
* */
void
printfmt(void (*putch)(int, void*, int), int fd, void *putdat, const char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
vprintfmt(putch, fd, putdat, fmt, ap);
va_end(ap);
}
/* *
* vprintfmt - format a string and print it by using putch, it's called with a va_list
* instead of a variable number of arguments
* @fd: file descriptor
* @putch: specified putch function, print a single character
* @putdat: used by @putch function
* @fmt: the format string to use
* @ap: arguments for the format string
*
* Call this function if you are already dealing with a va_list.
* Or you probably want printfmt() instead.
* */
void
vprintfmt(void (*putch)(int, void*, int), int fd, void *putdat, const char *fmt, va_list ap) {
register const char *p;
register int ch, err;
unsigned long long num;
int base, width, precision, lflag, altflag;
while (1) {
while ((ch = *(unsigned char *)fmt ++) != '%') {
if (ch == '\0') {
return;
}
putch(ch, putdat, fd);
}
// Process a %-escape sequence
char padc = ' ';
width = precision = -1;
lflag = altflag = 0;
reswitch:
switch (ch = *(unsigned char *)fmt ++) {
// flag to pad on the right
case '-':
padc = '-';
goto reswitch;
// flag to pad with 0's instead of spaces
case '0':
padc = '0';
goto reswitch;
// width field
case '1' ... '9':
for (precision = 0; ; ++ fmt) {
precision = precision * 10 + ch - '0';
ch = *fmt;
if (ch < '0' || ch > '9') {
break;
}
}
goto process_precision;
case '*':
precision = va_arg(ap, int);
goto process_precision;
case '.':
if (width < 0)
width = 0;
goto reswitch;
case '#':
altflag = 1;
goto reswitch;
process_precision:
if (width < 0)
width = precision, precision = -1;
goto reswitch;
// long flag (doubled for long long)
case 'l':
lflag ++;
goto reswitch;
// character
case 'c':
putch(va_arg(ap, int), putdat, fd);
break;
// error message
case 'e':
err = va_arg(ap, int);
if (err < 0) {
err = -err;
}
if (err > MAXERROR || (p = error_string[err]) == NULL) {
printfmt(putch, fd, putdat, "error %d", err);
}
else {
printfmt(putch, fd, putdat, "%s", p);
}
break;
// string
case 's':
if ((p = va_arg(ap, char *)) == NULL) {
p = "(null)";
}
if (width > 0 && padc != '-') {
for (width -= strnlen(p, precision); width > 0; width --) {
putch(padc, putdat, fd);
}
}
for (; (ch = *p ++) != '\0' && (precision < 0 || -- precision >= 0); width --) {
if (altflag && (ch < ' ' || ch > '~')) {
putch('?', putdat, fd);
}
else {
putch(ch, putdat, fd);
}
}
for (; width > 0; width --) {
putch(' ', putdat, fd);
}
break;
// (signed) decimal
case 'd':
num = getint(&ap, lflag);
if ((long long)num < 0) {
putch('-', putdat, fd);
num = -(long long)num;
}
base = 10;
goto number;
// unsigned decimal
case 'u':
num = getuint(&ap, lflag);
base = 10;
goto number;
// (unsigned) octal
case 'o':
num = getuint(&ap, lflag);
base = 8;
goto number;
// pointer
case 'p':
putch('0', putdat, fd);
putch('x', putdat, fd);
num = (unsigned long long)(uintptr_t)va_arg(ap, void *);
base = 16;
goto number;
// (unsigned) hexadecimal
case 'x':
num = getuint(&ap, lflag);
base = 16;
number:
printnum(putch, fd, putdat, num, base, width, padc);
break;
// escaped '%' character
case '%':
putch(ch, putdat, fd);
break;
// unrecognized escape sequence - just print it literally
default:
putch('%', putdat, fd);
for (fmt --; fmt[-1] != '%'; fmt --)
/* do nothing */;
break;
}
}
}
/* sprintbuf is used to save enough information of a buffer */
struct sprintbuf {
char *buf; // address pointer points to the first unused memory
char *ebuf; // points the end of the buffer
int cnt; // the number of characters that have been placed in this buffer
};
/* *
* sprintputch - 'print' a single character in a buffer
* @ch: the character will be printed
* @b: the buffer to place the character @ch
* */
static void
sprintputch(int ch, struct sprintbuf *b) {
b->cnt ++;
if (b->buf < b->ebuf) {
*b->buf ++ = ch;
}
}
/* *
* snprintf - format a string and place it in a buffer
* @str: the buffer to place the result into
* @size: the size of buffer, including the trailing null space
* @fmt: the format string to use
* */
int
snprintf(char *str, size_t size, const char *fmt, ...) {
va_list ap;
int cnt;
va_start(ap, fmt);
cnt = vsnprintf(str, size, fmt, ap);
va_end(ap);
return cnt;
}
/* *
* vsnprintf - format a string and place it in a buffer, it's called with a va_list
* instead of a variable number of arguments
* @str: the buffer to place the result into
* @size: the size of buffer, including the trailing null space
* @fmt: the format string to use
* @ap: arguments for the format string
*
* The return value is the number of characters which would be generated for the
* given input, excluding the trailing '\0'.
*
* Call this function if you are already dealing with a va_list.
* Or you probably want snprintf() instead.
* */
int
vsnprintf(char *str, size_t size, const char *fmt, va_list ap) {
struct sprintbuf b = {str, str + size - 1, 0};
if (str == NULL || b.buf > b.ebuf) {
return -E_INVAL;
}
// print the string to the buffer
vprintfmt((void*)sprintputch, NO_FD, &b, fmt, ap);
// null terminate the buffer
*b.buf = '\0';
return b.cnt;
}Last updated