stringbuf.c

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/*
    stringbuf: mimicking a bit of C++ to more safely handle strings
 
    copyright 2006-20 by the mpg123 project
        - free software under the terms of the LGPL 2.1
    see COPYING and AUTHORS files in distribution or http://mpg123.org
    initially written by Thomas Orgis
*/
 
#include "mpg123lib_intern.h"
#include "config.h"
#include "mpg123.h"
#include "compat.h"
#include <string.h>
#include "debug.h"
 
mpg123_string* attribute_align_arg mpg123_new_string(const char *val)
{
    mpg123_string *sb = malloc(sizeof(mpg123_string));
    if(!sb)
        return NULL;
    mpg123_init_string(sb);
    mpg123_set_string(sb, val);
    return sb;
}
 
void attribute_align_arg mpg123_delete_string(mpg123_string* sb)
{
    if(!sb)
        return;
    mpg123_free_string(sb);
    free(sb);
}
 
void attribute_align_arg mpg123_init_string(mpg123_string* sb)
{
    /* Handing in NULL here is a fatal mistake and rightfully so. */
    sb->p = NULL;
    sb->size = 0;
    sb->fill = 0;
}
 
void attribute_align_arg mpg123_free_string(mpg123_string* sb)
{
    if(!sb)
        return;
    if(sb->p != NULL) free(sb->p);
    mpg123_init_string(sb);
}
 
int attribute_align_arg mpg123_grow_string(mpg123_string* sb, size_t new)
{
    if(!sb)
        return 0;
    if(sb->size < new) return mpg123_resize_string(sb, new);
    else return 1;
}
 
int attribute_align_arg mpg123_resize_string(mpg123_string* sb, size_t new)
{
    if(!sb)
        return 0;
    debug3("resizing string pointer %p from %lu to %lu", (void*) sb->p, (unsigned long)sb->size, (unsigned long)new);
    if(new == 0)
    {
        if(sb->size && sb->p != NULL) free(sb->p);
        mpg123_init_string(sb);
        return 1;
    }
    if(sb->size != new)
    {
        char* t;
        debug("really!");
        t = (char*) safe_realloc(sb->p, new*sizeof(char));
        debug1("safe_realloc returned %p", (void*) t);
        if(t != NULL)
        {
            sb->p = t;
            sb->size = new;
            if(sb->size < sb->fill)
            {
                // Cut short the existing data, properly.
                sb->fill = sb->size;
                sb->p[sb->fill-1] = 0;
            }
            return 1;
        }
        else return 0;
    }
    else return 1; /* success */
}
 
int attribute_align_arg mpg123_copy_string(mpg123_string* from, mpg123_string* to)
{
    size_t fill;
    char  *text;
 
    debug2("called copy_string with %p -> %p", (void*)from, (void*)to);
    if(to == NULL)
        return 0;
    if(from == NULL)
    {
        fill = 0;
        text = NULL;
    }
    else
    {
        fill = from->fill;
        text = from->p;
    }
 
    if(mpg123_resize_string(to, fill))
    {
        if(fill) /* Avoid memcpy(NULL, NULL, 0) */
            memcpy(to->p, text, fill);
        to->fill = fill;
        return 1;
    }
    else return 0;
}
 
int attribute_align_arg mpg123_move_string(mpg123_string *from, mpg123_string *to)
{
    if(to)
        mpg123_free_string(to);
    else
        mpg123_free_string(from);
    if(from && to)
        *to = *from;
    if(from)
        mpg123_init_string(from);
    return (from && to) ? 1 : 0;
}
 
int attribute_align_arg mpg123_add_string(mpg123_string* sb, const char* stuff)
{
    debug1("adding %s", stuff);
    return mpg123_add_substring(sb, stuff, 0, stuff ? strlen(stuff) : 0);
}
 
int attribute_align_arg mpg123_add_substring(mpg123_string *sb, const char *stuff, size_t from, size_t count)
{
    debug("adding a substring");
    if(!sb || !stuff)
        return 0;
    if(sb->fill) /* includes zero byte... */
    {
        if( (SIZE_MAX - sb->fill >= count) /* Avoid overflow. */
            && (sb->size >= sb->fill+count || mpg123_grow_string(sb, sb->fill+count)) )
        {
            memcpy(sb->p+sb->fill-1, stuff+from, count);
            sb->fill += count;
            sb->p[sb->fill-1] = 0; /* Terminate! */
        }
        else return 0;
    }
    else
    {
        if( count < SIZE_MAX && mpg123_grow_string(sb, count+1) )
        {
            memcpy(sb->p, stuff+from, count);
            sb->fill = count+1;
            sb->p[sb->fill-1] = 0; /* Terminate! */
        }
        else return 0;
    }
    return 1;
}
 
int attribute_align_arg mpg123_set_substring(mpg123_string* sb, const char* stuff, size_t from, size_t count)
{
    if(!sb)
        return 0;
    sb->fill = 0;
    return mpg123_add_substring(sb, stuff, from, count);
}
 
int attribute_align_arg mpg123_set_string(mpg123_string* sb, const char* stuff)
{
    if(!sb)
        return 0;
    sb->fill = 0;
    return mpg123_add_string(sb, stuff);
}
 
size_t attribute_align_arg mpg123_strlen(mpg123_string *sb, int utf8)
{
    size_t i;
    size_t bytelen;
 
    /* Notions of empty string. If there's only a single character, it has to be the trailing zero, and if the first is the trailing zero anyway, we got empty. */
    if(!sb || sb->fill < 2 || sb->p[0] == 0) return 0;
 
    /* Find the first non-null character from the back.
       We already established that the first character is non-null
       That at fill-2 has to be null, though. */
    for(i=sb->fill-2; i>0; --i)
    if(sb->p[i] != 0) break;
 
    /* For simple byte strings, we are done now. */
    bytelen = i+1;
 
    if(!utf8) return bytelen;
    else
    {
        /* Work out the actual count of UTF8 bytes.
           This employs no particular encoding error checking. */
        size_t len = 0;
        for(i=0; i<bytelen; ++i)
        {
            /* Every byte that is not a continuation byte ( 0xc0 == 10xx xxxx ) stands for a character. */
            if((sb->p[i] & 0xc0) != 0x80) len++;
        }
        return len;
    }
}
 
int attribute_align_arg mpg123_chomp_string(mpg123_string *sb)
{
    ssize_t i;
    if(!sb || !sb->fill) return 0;
 
    /* Ensure that it is zero-terminated. */
    sb->p[sb->fill-1] = 0;
    for(i=sb->fill-2; i>=0; --i)
    {
        char *c = sb->p+i;
        /* Stop at the first proper character. */
        if(*c && *c != '\r' && *c != '\n') break;
        else *c = 0;
    }
    /* initial fill at least 1, so i at least -1,
       +2 means nothing happened for fill=1 .
       With i=0, we got one non-null character, fill shall be 2
       to accomodate the trailing zero. */
    sb->fill = (size_t)i+2;
 
    return 1;
}
 
int attribute_align_arg mpg123_same_string(mpg123_string *a, mpg123_string *b)
{
    if(!a || !b)
        return 0;
    if(a->fill != b->fill)
        return 0;
    if(memcmp(a->p, b->p, a->fill))
        return 0;
    return 1;
}