[FFmpeg-devel] [PATCH 1/2] lavu: add locale-independent sscanf implementation

Michael Niedermayer michael at niedermayer.cc
Mon Nov 12 21:08:32 EET 2018


On Mon, Nov 12, 2018 at 07:46:45PM +0100, Paul B Mahol wrote:
> Copied and adopted from musl implementation.
>  * converted all 'long double' to 'double'
> 
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  libavutil/avstring.c | 961 +++++++++++++++++++++++++++++++++++++++++++
>  libavutil/avstring.h |   6 +
>  2 files changed, 967 insertions(+)
[...]
> +static int ff_vfscanf(FFFILE *f, const char *fmt, va_list ap)
> +{
> +    int width;
> +    int size;
> +    int base;
> +    const unsigned char *p;
> +    int c, t;
> +    char *s;
> +    void *dest=NULL;
> +    int invert;
> +    int matches=0;
> +    unsigned long long x;
> +    double y;
> +    off_t pos = 0;
> +    unsigned char scanset[257];
> +    size_t i, k;
> +
> +    for (p=(const unsigned char *)fmt; *p; p++) {
> +
> +        if (av_isspace(*p)) {
> +            while (av_isspace(p[1])) p++;
> +            shlim(f, 0);
> +            while (av_isspace(shgetc(f)));
> +            shunget(f);
> +            pos += shcnt(f);
> +            continue;
> +        }
> +        if (*p != '%' || p[1] == '%') {
> +            shlim(f, 0);
> +            if (*p == '%') {
> +                p++;
> +                while (av_isspace((c=shgetc(f))));
> +            } else {
> +                c = shgetc(f);
> +            }
> +            if (c!=*p) {
> +                shunget(f);
> +                if (c<0) goto input_fail;
> +                goto match_fail;
> +            }
> +            pos += shcnt(f);
> +            continue;
> +        }
> +
> +        p++;
> +        if (*p=='*') {
> +            dest = 0; p++;
> +        } else if (av_isdigit(*p) && p[1]=='$') {
> +            dest = arg_n(ap, *p-'0'); p+=2;
> +        } else {
> +            dest = va_arg(ap, void *);
> +        }
> +
> +        for (width=0; av_isdigit(*p); p++) {
> +            width = 10*width + *p - '0';
> +        }
> +
> +        if (*p=='m') {
> +            s = 0;
> +            p++;
> +        }
> +
> +        size = SIZE_def;
> +        switch (*p++) {
> +        case 'h':
> +            if (*p == 'h') p++, size = SIZE_hh;
> +            else size = SIZE_h;
> +            break;
> +        case 'l':
> +            if (*p == 'l') p++, size = SIZE_ll;
> +            else size = SIZE_l;
> +            break;
> +        case 'j':
> +            size = SIZE_ll;
> +            break;
> +        case 'z':
> +        case 't':
> +            size = SIZE_l;
> +            break;
> +        case 'L':
> +            size = SIZE_L;
> +            break;
> +        case 'd': case 'i': case 'o': case 'u': case 'x':
> +        case 'a': case 'e': case 'f': case 'g':
> +        case 'A': case 'E': case 'F': case 'G': case 'X':
> +        case 's': case 'c': case '[':
> +        case 'S': case 'C':
> +        case 'p': case 'n':
> +            p--;
> +            break;
> +        default:
> +            goto fmt_fail;
> +        }
> +
> +        t = *p;
> +
> +        /* C or S */
> +        if ((t&0x2f) == 3) {
> +            t |= 32;
> +            size = SIZE_l;
> +        }
> +
> +        switch (t) {
> +            case 'c':
> +                if (width < 1) width = 1;
> +            case '[':
> +                break;
> +            case 'n':
> +                store_int(dest, size, pos);
> +                /* do not increment match count, etc! */
> +                continue;
> +            default:
> +                shlim(f, 0);
> +                while (av_isspace(shgetc(f)));
> +                shunget(f);
> +                pos += shcnt(f);
> +        }
> +
> +        shlim(f, width);
> +        if (shgetc(f) < 0) goto input_fail;
> +        shunget(f);
> +
> +        switch (t) {
> +            case 's':
> +            case 'c':
> +            case '[':
> +                if (t == 'c' || t == 's') {
> +                    memset(scanset, -1, sizeof scanset);
> +                    scanset[0] = 0;
> +                    if (t == 's') {
> +                        scanset[1+'\t'] = 0;
> +                        scanset[1+'\n'] = 0;
> +                        scanset[1+'\v'] = 0;
> +                        scanset[1+'\f'] = 0;
> +                        scanset[1+'\r'] = 0;
> +                        scanset[1+' '] = 0;
> +                    }
> +                } else {
> +                    if (*++p == '^') p++, invert = 1;
> +                    else invert = 0;
> +                    memset(scanset, invert, sizeof scanset);
> +                    scanset[0] = 0;
> +                    if (*p == '-') p++, scanset[1+'-'] = 1-invert;
> +                    else if (*p == ']') p++, scanset[1+']'] = 1-invert;
> +                    for (; *p != ']'; p++) {
> +                        if (!*p) goto fmt_fail;
> +                        if (*p=='-' && p[1] && p[1] != ']')
> +                            for (c=p++[-1]; c<*p; c++)
> +                                scanset[1+c] = 1-invert;
> +                        scanset[1+*p] = 1-invert;
> +                    }
> +                }
> +                s = 0;
> +                i = 0;

> +                k = t=='c' ? width+1U : 31;

k is set but not used


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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