/*-
 * Copyright (c) 2003-2007 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "bsdtar_platform.h"
__FBSDID("$FreeBSD: src/usr.bin/tar/util.c,v 1.23 2008/12/15 06:00:25 kientzle Exp $");

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>  /* Linux doesn't define mode_t, etc. in sys/stat.h. */
#endif
#include <ctype.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_IO_H
#include <io.h>
#endif
#ifdef HAVE_STDARG_H
#include <stdarg.h>
#endif
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_WCTYPE_H
#include <wctype.h>
#else
/* If we don't have wctype, we need to hack up some version of iswprint(). */
#define iswprint isprint
#endif

#include "bsdtar.h"
#include "err.h"

static size_t   bsdtar_expand_char(char *, size_t, char);
static const char *strip_components(const char *path, int elements);

/* TODO:  Hack up a version of mbtowc for platforms with no wide
 * character support at all.  I think the following might suffice,
 * but it needs careful testing.
 * #if !HAVE_MBTOWC
 * #define mbtowc(wcp, p, n) ((*wcp = *p), 1)
 * #endif
 */

/*
 * Print a string, taking care with any non-printable characters.
 *
 * Note that we use a stack-allocated buffer to receive the formatted
 * string if we can.  This is partly performance (avoiding a call to
 * malloc()), partly out of expedience (we have to call vsnprintf()
 * before malloc() anyway to find out how big a buffer we need; we may
 * as well point that first call at a small local buffer in case it
 * works), but mostly for safety (so we can use this to print messages
 * about out-of-memory conditions).
 */

void
safe_fprintf(FILE *f, const char *fmt, ...)
{
    char fmtbuff_stack[256]; /* Place to format the printf() string. */
    char outbuff[256]; /* Buffer for outgoing characters. */
    char *fmtbuff_heap; /* If fmtbuff_stack is too small, we use malloc */
    char *fmtbuff;  /* Pointer to fmtbuff_stack or fmtbuff_heap. */
    int fmtbuff_length;
    int length, n;
    va_list ap;
    const char *p;
    unsigned i;
    wchar_t wc;
    char try_wc;

    /* Use a stack-allocated buffer if we can, for speed and safety. */
    fmtbuff_heap = NULL;
    fmtbuff_length = sizeof(fmtbuff_stack);
    fmtbuff = fmtbuff_stack;

    /* Try formatting into the stack buffer. */
    va_start(ap, fmt);
    length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
    va_end(ap);

    /* If the result was too large, allocate a buffer on the heap. */
    if (length >= fmtbuff_length) {
        fmtbuff_length = length+1;
        fmtbuff_heap = malloc(fmtbuff_length);

        /* Reformat the result into the heap buffer if we can. */
        if (fmtbuff_heap != NULL) {
            fmtbuff = fmtbuff_heap;
            va_start(ap, fmt);
            length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
            va_end(ap);
        } else {
            /* Leave fmtbuff pointing to the truncated
             * string in fmtbuff_stack. */
            length = sizeof(fmtbuff_stack) - 1;
        }
    }

    /* Note: mbrtowc() has a cleaner API, but mbtowc() seems a bit
     * more portable, so we use that here instead. */
    n = mbtowc(NULL, NULL, 1); /* Reset the shift state. */

    /* Write data, expanding unprintable characters. */
    p = fmtbuff;
    i = 0;
    try_wc = 1;
    while (*p != '\0') {

        /* Convert to wide char, test if the wide
         * char is printable in the current locale. */
        if (try_wc && (n = mbtowc(&wc, p, length)) != -1) {
            length -= n;
            if (iswprint(wc) && wc != L'\\') {
                /* Printable, copy the bytes through. */
                while (n-- > 0)
                    outbuff[i++] = *p++;
            } else {
                /* Not printable, format the bytes. */
                while (n-- > 0)
                    i += bsdtar_expand_char(
                        outbuff, i, *p++);
            }
        } else {
            /* After any conversion failure, don't bother
             * trying to convert the rest. */
            i += bsdtar_expand_char(outbuff, i, *p++);
            try_wc = 0;
        }

        /* If our output buffer is full, dump it and keep going. */
        if (i > (sizeof(outbuff) - 20)) {
            outbuff[i++] = '\0';
            fprintf(f, "%s", outbuff);
            i = 0;
        }
    }
    outbuff[i++] = '\0';
    fprintf(f, "%s", outbuff);

    /* If we allocated a heap-based formatting buffer, free it now. */
    if (fmtbuff_heap != NULL)
        free(fmtbuff_heap);
}

/*
 * Render an arbitrary sequence of bytes into printable ASCII characters.
 */
static size_t
bsdtar_expand_char(char *buff, size_t offset, char c)
{
    size_t i = offset;

    if (isprint((unsigned char)c) && c != '\\')
        buff[i++] = c;
    else {
        buff[i++] = '\\';
        switch (c) {
        case '\a': buff[i++] = 'a'; break;
        case '\b': buff[i++] = 'b'; break;
        case '\f': buff[i++] = 'f'; break;
        case '\n': buff[i++] = 'n'; break;
#if '\r' != '\n'
        /* On some platforms, \n and \r are the same. */
        case '\r': buff[i++] = 'r'; break;
#endif
        case '\t': buff[i++] = 't'; break;
        case '\v': buff[i++] = 'v'; break;
        case '\\': buff[i++] = '\\'; break;
        default:
            sprintf(buff + i, "%03o", 0xFF & (int)c);
            i += 3;
        }
    }

    return (i - offset);
}

int
yes(const char *fmt, ...)
{
    char buff[32];
    char *p;
    ssize_t l;

    va_list ap;
    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);
    fprintf(stderr, " (y/N)? ");
    fflush(stderr);

    l = read(2, buff, sizeof(buff) - 1);
    if (l <= 0)
        return (0);
    buff[l] = 0;

    for (p = buff; *p != '\0'; p++) {
        if (isspace((unsigned char)*p))
            continue;
        switch(*p) {
        case 'y': case 'Y':
            return (1);
        case 'n': case 'N':
            return (0);
        default:
            return (0);
        }
    }

    return (0);
}

/*-
 * The logic here for -C <dir> attempts to avoid
 * chdir() as long as possible.  For example:
 * "-C /foo -C /bar file"          needs chdir("/bar") but not chdir("/foo")
 * "-C /foo -C bar file"           needs chdir("/foo/bar")
 * "-C /foo -C bar /file1"         does not need chdir()
 * "-C /foo -C bar /file1 file2"   needs chdir("/foo/bar") before file2
 *
 * The only correct way to handle this is to record a "pending" chdir
 * request and combine multiple requests intelligently until we
 * need to process a non-absolute file.  set_chdir() adds the new dir
 * to the pending list; do_chdir() actually executes any pending chdir.
 *
 * This way, programs that build tar command lines don't have to worry
 * about -C with non-existent directories; such requests will only
 * fail if the directory must be accessed.
 *
 * TODO: Make this handle Windows paths correctly.
 */
void
set_chdir(struct bsdtar *bsdtar, const char *newdir)
{
    if (newdir[0] == '/') {
        /* The -C /foo -C /bar case; dump first one. */
        free(bsdtar->pending_chdir);
        bsdtar->pending_chdir = NULL;
    }
    if (bsdtar->pending_chdir == NULL)
        /* Easy case: no previously-saved dir. */
        bsdtar->pending_chdir = strdup(newdir);
    else {
        /* The -C /foo -C bar case; concatenate */
        char *old_pending = bsdtar->pending_chdir;
        size_t old_len = strlen(old_pending);
        bsdtar->pending_chdir = malloc(old_len + strlen(newdir) + 2);
        if (old_pending[old_len - 1] == '/')
            old_pending[old_len - 1] = '\0';
        if (bsdtar->pending_chdir != NULL)
            sprintf(bsdtar->pending_chdir, "%s/%s",
                old_pending, newdir);
        free(old_pending);
    }
    if (bsdtar->pending_chdir == NULL)
        lafe_errc(1, errno, "No memory");
}

void
do_chdir(struct bsdtar *bsdtar)
{
    if (bsdtar->pending_chdir == NULL)
        return;

    if (chdir(bsdtar->pending_chdir) != 0) {
        lafe_errc(1, 0, "could not chdir to '%s'\n",
            bsdtar->pending_chdir);
    }
    free(bsdtar->pending_chdir);
    bsdtar->pending_chdir = NULL;
}

const char *
strip_components(const char *p, int elements)
{
    /* Skip as many elements as necessary. */
    while (elements > 0) {
        switch (*p++) {
        case '/':
#if defined(_WIN32) && !defined(__CYGWIN__)
        case '\\': /* Support \ path sep on Windows ONLY. */
#endif
            elements--;
            break;
        case '\0':
            /* Path is too short, skip it. */
            return (NULL);
        }
    }

    /* Skip any / characters.  This handles short paths that have
     * additional / termination.  This also handles the case where
     * the logic above stops in the middle of a duplicate //
     * sequence (which would otherwise get converted to an
     * absolute path). */
    for (;;) {
        switch (*p) {
        case '/':
#if defined(_WIN32) && !defined(__CYGWIN__)
        case '\\': /* Support \ path sep on Windows ONLY. */
#endif
            ++p;
            break;
        case '\0':
            return (NULL);
        default:
            return (p);
        }
    }
}

/*
 * Handle --strip-components and any future path-rewriting options.
 * Returns non-zero if the pathname should not be extracted.
 *
 * TODO: Support pax-style regex path rewrites.
 */
int
edit_pathname(struct bsdtar *bsdtar, struct archive_entry *entry)
{
    const char *name = archive_entry_pathname(entry);
#if HAVE_REGEX_H
    char *subst_name;
    int r;
#endif

#if HAVE_REGEX_H
    r = apply_substitution(bsdtar, name, &subst_name, 0);
    if (r == -1) {
        lafe_warnc(0, "Invalid substitution, skipping entry");
        return 1;
    }
    if (r == 1) {
        archive_entry_copy_pathname(entry, subst_name);
        if (*subst_name == '\0') {
            free(subst_name);
            return -1;
        } else
            free(subst_name);
        name = archive_entry_pathname(entry);
    }

    if (archive_entry_hardlink(entry)) {
        r = apply_substitution(bsdtar, archive_entry_hardlink(entry), &subst_name, 1);
        if (r == -1) {
            lafe_warnc(0, "Invalid substitution, skipping entry");
            return 1;
        }
        if (r == 1) {
            archive_entry_copy_hardlink(entry, subst_name);
            free(subst_name);
        }
    }
    if (archive_entry_symlink(entry) != NULL) {
        r = apply_substitution(bsdtar, archive_entry_symlink(entry), &subst_name, 1);
        if (r == -1) {
            lafe_warnc(0, "Invalid substitution, skipping entry");
            return 1;
        }
        if (r == 1) {
            archive_entry_copy_symlink(entry, subst_name);
            free(subst_name);
        }
    }
#endif

    /* Strip leading dir names as per --strip-components option. */
    if (bsdtar->strip_components > 0) {
        const char *linkname = archive_entry_hardlink(entry);

        name = strip_components(name, bsdtar->strip_components);
        if (name == NULL)
            return (1);

        if (linkname != NULL) {
            linkname = strip_components(linkname,
                bsdtar->strip_components);
            if (linkname == NULL)
                return (1);
            archive_entry_copy_hardlink(entry, linkname);
        }
    }

    /* By default, don't write or restore absolute pathnames. */
    if (!bsdtar->option_absolute_paths) {
        const char *rp, *p = name;
        int slashonly = 1;

        /* Remove leading "//./" or "//?/" or "//?/UNC/"
         * (absolute path prefixes used by Windows API) */
        if ((p[0] == '/' || p[0] == '\\') &&
            (p[1] == '/' || p[1] == '\\') &&
            (p[2] == '.' || p[2] == '?') &&
            (p[3] == '/' || p[3] == '\\'))
        {
            if (p[2] == '?' &&
                (p[4] == 'U' || p[4] == 'u') &&
                (p[5] == 'N' || p[5] == 'n') &&
                (p[6] == 'C' || p[6] == 'c') &&
                (p[7] == '/' || p[7] == '\\'))
                p += 8;
            else
                p += 4;
            slashonly = 0;
        }
        do {
            rp = p;
            /* Remove leading drive letter from archives created
             * on Windows. */
            if (((p[0] >= 'a' && p[0] <= 'z') ||
                 (p[0] >= 'A' && p[0] <= 'Z')) &&
                 p[1] == ':') {
                p += 2;
                slashonly = 0;
            }
            /* Remove leading "/../", "//", etc. */
            while (p[0] == '/' || p[0] == '\\') {
                if (p[1] == '.' && p[2] == '.' &&
                    (p[3] == '/' || p[3] == '\\')) {
                    p += 3; /* Remove "/..", leave "/"
                             * for next pass. */
                    slashonly = 0;
                } else
                    p += 1; /* Remove "/". */
            }
        } while (rp != p);

        if (p != name && !bsdtar->warned_lead_slash) {
            /* Generate a warning the first time this happens. */
            if (slashonly)
                lafe_warnc(0,
                    "Removing leading '%c' from member names",
                    name[0]);
            else
                lafe_warnc(0,
                    "Removing leading drive letter from "
                    "member names");
            bsdtar->warned_lead_slash = 1;
        }

        /* Special case: Stripping everything yields ".". */
        if (*p == '\0')
            name = ".";
        else
            name = p;
    } else {
        /* Strip redundant leading '/' characters. */
        while (name[0] == '/' && name[1] == '/')
            name++;
    }

    /* Safely replace name in archive_entry. */
    if (name != archive_entry_pathname(entry)) {
        char *q = strdup(name);
        archive_entry_copy_pathname(entry, q);
        free(q);
    }
    return (0);
}

/*
 * Like strcmp(), but try to be a little more aware of the fact that
 * we're comparing two paths.  Right now, it just handles leading
 * "./" and trailing '/' specially, so that "a/b/" == "./a/b"
 *
 * TODO: Make this better, so that "./a//b/./c/" == "a/b/c"
 * TODO: After this works, push it down into libarchive.
 * TODO: Publish the path normalization routines in libarchive so
 * that bsdtar can normalize paths and use fast strcmp() instead
 * of this.
 *
 * Note: This is currently only used within write.c, so should
 * not handle \ path separators.
 */

int
pathcmp(const char *a, const char *b)
{
    /* Skip leading './' */
    if (a[0] == '.' && a[1] == '/' && a[2] != '\0')
        a += 2;
    if (b[0] == '.' && b[1] == '/' && b[2] != '\0')
        b += 2;
    /* Find the first difference, or return (0) if none. */
    while (*a == *b) {
        if (*a == '\0')
            return (0);
        a++;
        b++;
    }
    /*
     * If one ends in '/' and the other one doesn't,
     * they're the same.
     */
    if (a[0] == '/' && a[1] == '\0' && b[0] == '\0')
        return (0);
    if (a[0] == '\0' && b[0] == '/' && b[1] == '\0')
        return (0);
    /* They're really different, return the correct sign. */
    return (*(const unsigned char *)a - *(const unsigned char *)b);
}
