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#include "util.h"

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#include <string.h>

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#include <errno.h>

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int chfext (char *buf, size_t len, const char *newext)

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{

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    char *ext;

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    // find .ext

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    if ((ext = strrchr(buf, '.')) == NULL) {

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        errno = EINVAL;

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        return -1;

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    }

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    // check length

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    if (ext + strlen(newext) >= buf + len) {

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        errno = ENAMETOOLONG;

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        return -1;

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    }

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    // change to .foo

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    strcpy(ext, newext);

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    // ok

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    return 0;

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}

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int path_with_fext (const char *path, char *buf, size_t len, const char *newext)

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{

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    // verify length

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    if (strlen(path) > len) {

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        errno = ENAMETOOLONG;

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        return -1;

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    }

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    // copy filename

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    strcpy(buf, path);

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    // change fext

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    return chfext(buf, len, newext);

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}