vsprintf.c

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/*
 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stddef.h>
#include <stdarg.h>
#include <stdio.h>
#include <console.h>
#include <errno.h>
#include <gpxe/vsprintf.h>

/** @file */

#define CHAR_LEN        0       /**< "hh" length modifier */
#define SHORT_LEN       1       /**< "h" length modifier */
#define INT_LEN         2       /**< no length modifier */
#define LONG_LEN        3       /**< "l" length modifier */
#define LONGLONG_LEN    4       /**< "ll" length modifier */
#define SIZE_T_LEN      5       /**< "z" length modifier */

static uint8_t type_sizes[] = {
        [CHAR_LEN]      = sizeof ( char ),
        [SHORT_LEN]     = sizeof ( short ),
        [INT_LEN]       = sizeof ( int ),
        [LONG_LEN]      = sizeof ( long ),
        [LONGLONG_LEN]  = sizeof ( long long ),
        [SIZE_T_LEN]    = sizeof ( size_t ),
};

/**
 * Use lower-case for hexadecimal digits
 *
 * Note that this value is set to 0x20 since that makes for very
 * efficient calculations.  (Bitwise-ORing with @c LCASE converts to a
 * lower-case character, for example.)
 */
#define LCASE 0x20

/**
 * Use "alternate form"
 *
 * For hexadecimal numbers, this means to add a "0x" or "0X" prefix to
 * the number.
 */
#define ALT_FORM 0x02

/**
 * Format a hexadecimal number
 *
 * @v end               End of buffer to contain number
 * @v num               Number to format
 * @v width             Minimum field width
 * @ret ptr             End of buffer
 *
 * Fills a buffer in reverse order with a formatted hexadecimal
 * number.  The number will be zero-padded to the specified width.
 * Lower-case and "alternate form" (i.e. "0x" prefix) flags may be
 * set.
 *
 * There must be enough space in the buffer to contain the largest
 * number that this function can format.
 */
static char * format_hex ( char *end, unsigned long long num, int width,
                           int flags ) {
        char *ptr = end;
        int case_mod;

        /* Generate the number */
        case_mod = flags & LCASE;
        do {
                *(--ptr) = "0123456789ABCDEF"[ num & 0xf ] | case_mod;
                num >>= 4;
        } while ( num );

        /* Zero-pad to width */
        while ( ( end - ptr ) < width )
                *(--ptr) = '0';

        /* Add "0x" or "0X" if alternate form specified */
        if ( flags & ALT_FORM ) {
                *(--ptr) = 'X' | case_mod;
                *(--ptr) = '0';
        }

        return ptr;
}

/**
 * Format a decimal number
 *
 * @v end               End of buffer to contain number
 * @v num               Number to format
 * @v width             Minimum field width
 * @ret ptr             End of buffer
 *
 * Fills a buffer in reverse order with a formatted decimal number.
 * The number will be space-padded to the specified width.
 *
 * There must be enough space in the buffer to contain the largest
 * number that this function can format.
 */
static char * format_decimal ( char *end, signed long num, int width ) {
        char *ptr = end;
        int negative = 0;

        /* Generate the number */
        if ( num < 0 ) {
                negative = 1;
                num = -num;
        }
        do {
                *(--ptr) = '0' + ( num % 10 );
                num /= 10;
        } while ( num );

        /* Add "-" if necessary */
        if ( negative )
                *(--ptr) = '-';

        /* Space-pad to width */
        while ( ( end - ptr ) < width )
                *(--ptr) = ' ';

        return ptr;
}

/**
 * Print character via a printf context
 *
 * @v ctx               Context
 * @v c                 Character
 *
 * Call's the printf_context::handler() method and increments
 * printf_context::len.
 */
static inline void cputchar ( struct printf_context *ctx, unsigned int c ) {
        ctx->handler ( ctx, c );
        ++ctx->len;
}

/**
 * Write a formatted string to a printf context
 *
 * @v ctx               Context
 * @v fmt               Format string
 * @v args              Arguments corresponding to the format string
 * @ret len             Length of formatted string
 */
size_t vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
        int flags;
        int width;
        uint8_t *length;
        char *ptr;
        char tmp_buf[32]; /* 32 is enough for all numerical formats.
                           * Insane width fields could overflow this buffer. */

        /* Initialise context */
        ctx->len = 0;

        for ( ; *fmt ; fmt++ ) {
                /* Pass through ordinary characters */
                if ( *fmt != '%' ) {
                        cputchar ( ctx, *fmt );
                        continue;
                }
                fmt++;
                /* Process flag characters */
                flags = 0;
                for ( ; ; fmt++ ) {
                        if ( *fmt == '#' ) {
                                flags |= ALT_FORM;
                        } else if ( *fmt == '0' ) {
                                /* We always 0-pad hex and space-pad decimal */
                        } else {
                                /* End of flag characters */
                                break;
                        }
                }
                /* Process field width */
                width = 0;
                for ( ; ; fmt++ ) {
                        if ( ( ( unsigned ) ( *fmt - '0' ) ) < 10 ) {
                                width = ( width * 10 ) + ( *fmt - '0' );
                        } else {
                                break;
                        }
                }
                /* We don't do floating point */
                /* Process length modifier */
                length = &type_sizes[INT_LEN];
                for ( ; ; fmt++ ) {
                        if ( *fmt == 'h' ) {
                                length--;
                        } else if ( *fmt == 'l' ) {
                                length++;
                        } else if ( *fmt == 'z' ) {
                                length = &type_sizes[SIZE_T_LEN];
                        } else {
                                break;
                        }
                }
                /* Process conversion specifier */
                ptr = tmp_buf + sizeof ( tmp_buf ) - 1;
                *ptr = '\0';
                if ( *fmt == 'c' ) {
                        cputchar ( ctx, va_arg ( args, unsigned int ) );
                } else if ( *fmt == 's' ) {
                        ptr = va_arg ( args, char * );
                        if ( ! ptr )
                                ptr = "<NULL>";
                } else if ( *fmt == 'p' ) {
                        intptr_t ptrval;

                        ptrval = ( intptr_t ) va_arg ( args, void * );
                        ptr = format_hex ( ptr, ptrval, width, 
                                           ( ALT_FORM | LCASE ) );
                } else if ( ( *fmt & ~0x20 ) == 'X' ) {
                        unsigned long long hex;

                        flags |= ( *fmt & 0x20 ); /* LCASE */
                        if ( *length >= sizeof ( unsigned long long ) ) {
                                hex = va_arg ( args, unsigned long long );
                        } else if ( *length >= sizeof ( unsigned long ) ) {
                                hex = va_arg ( args, unsigned long );
                        } else {
                                hex = va_arg ( args, unsigned int );
                        }
                        ptr = format_hex ( ptr, hex, width, flags );
                } else if ( ( *fmt == 'd' ) || ( *fmt == 'i' ) ){
                        signed long decimal;

                        if ( *length >= sizeof ( signed long ) ) {
                                decimal = va_arg ( args, signed long );
                        } else {
                                decimal = va_arg ( args, signed int );
                        }
                        ptr = format_decimal ( ptr, decimal, width );
                } else {
                        *(--ptr) = *fmt;
                }
                /* Write out conversion result */
                for ( ; *ptr ; ptr++ ) {
                        cputchar ( ctx, *ptr );
                }
        }

        return ctx->len;
}

/** Context used by vsnprintf() and friends */
struct sputc_context {
        struct printf_context ctx;
        /** Buffer for formatted string (used by printf_sputc()) */
        char *buf;
        /** Buffer length (used by printf_sputc()) */
        size_t max_len; 
};

/**
 * Write character to buffer
 *
 * @v ctx               Context
 * @v c                 Character
 */
static void printf_sputc ( struct printf_context *ctx, unsigned int c ) {
        struct sputc_context * sctx =
                container_of ( ctx, struct sputc_context, ctx );

        if ( ctx->len < sctx->max_len )
                sctx->buf[ctx->len] = c;
}

/**
 * Write a formatted string to a buffer
 *
 * @v buf               Buffer into which to write the string
 * @v size              Size of buffer
 * @v fmt               Format string
 * @v args              Arguments corresponding to the format string
 * @ret len             Length of formatted string
 *
 * If the buffer is too small to contain the string, the returned
 * length is the length that would have been written had enough space
 * been available.
 */
int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args ) {
        struct sputc_context sctx;
        size_t len;
        size_t end;

        /* Hand off to vcprintf */
        sctx.ctx.handler = printf_sputc;
        sctx.buf = buf;
        sctx.max_len = size;
        len = vcprintf ( &sctx.ctx, fmt, args );

        /* Add trailing NUL */
        if ( size ) {
                end = size - 1;
                if ( len < end )
                        end = len;
                buf[end] = '\0';
        }

        return len;
}

/**
 * Write a formatted string to a buffer
 *
 * @v buf               Buffer into which to write the string
 * @v size              Size of buffer
 * @v fmt               Format string
 * @v ...               Arguments corresponding to the format string
 * @ret len             Length of formatted string
 */
int snprintf ( char *buf, size_t size, const char *fmt, ... ) {
        va_list args;
        int i;

        va_start ( args, fmt );
        i = vsnprintf ( buf, size, fmt, args );
        va_end ( args );
        return i;
}

/**
 * Version of vsnprintf() that accepts a signed buffer size
 *
 * @v buf               Buffer into which to write the string
 * @v size              Size of buffer
 * @v fmt               Format string
 * @v args              Arguments corresponding to the format string
 * @ret len             Length of formatted string
 */
int vssnprintf ( char *buf, ssize_t ssize, const char *fmt, va_list args ) {

        /* Treat negative buffer size as zero buffer size */
        if ( ssize < 0 )
                ssize = 0;

        /* Hand off to vsnprintf */
        return vsnprintf ( buf, ssize, fmt, args );
}

/**
 * Version of vsnprintf() that accepts a signed buffer size
 *
 * @v buf               Buffer into which to write the string
 * @v size              Size of buffer
 * @v fmt               Format string
 * @v ...               Arguments corresponding to the format string
 * @ret len             Length of formatted string
 */
int ssnprintf ( char *buf, ssize_t ssize, const char *fmt, ... ) {
        va_list args;
        int len;

        /* Hand off to vssnprintf */
        va_start ( args, fmt );
        len = vssnprintf ( buf, ssize, fmt, args );
        va_end ( args );
        return len;
}

/**
 * Write character to console
 *
 * @v ctx               Context
 * @v c                 Character
 */
static void printf_putchar ( struct printf_context *ctx __unused,
                             unsigned int c ) {
        putchar ( c );
}

/**
 * Write a formatted string to the console
 *
 * @v fmt               Format string
 * @v args              Arguments corresponding to the format string
 * @ret len             Length of formatted string
 */
int vprintf ( const char *fmt, va_list args ) {
        struct printf_context ctx;

        /* Hand off to vcprintf */
        ctx.handler = printf_putchar;   
        return vcprintf ( &ctx, fmt, args );    
}

/**
 * Write a formatted string to the console.
 *
 * @v fmt               Format string
 * @v ...               Arguments corresponding to the format string
 * @ret len             Length of formatted string
 */
int printf ( const char *fmt, ... ) {
        va_list args;
        int i;

        va_start ( args, fmt );
        i = vprintf ( fmt, args );
        va_end ( args );
        return i;
}