gitweb: Improve installation instructions in gitweb/INSTALL

[git/jnareb-git/bp-gitweb.git] / quote.c

#include "cache.h"
#include "quote.h"

int quote_path_fully = 1;

/* Help to copy the thing properly quoted for the shell safety.
 * any single quote is replaced with '\'', any exclamation point
 * is replaced with '\!', and the whole thing is enclosed in a
 *
 * E.g.
 *  original     sq_quote     result
 *  name     ==> name      ==> 'name'
 *  a b      ==> a b       ==> 'a b'
 *  a'b      ==> a'\''b    ==> 'a'\''b'
 *  a!b      ==> a'\!'b    ==> 'a'\!'b'
 */
static inline int need_bs_quote(char c)
{
        return (c == '\'' || c == '!');
}

void sq_quote_buf(struct strbuf *dst, const char *src)
{
        char *to_free = NULL;

        if (dst->buf == src)
                to_free = strbuf_detach(dst, NULL);

        strbuf_addch(dst, '\'');
        while (*src) {
                size_t len = strcspn(src, "'!");
                strbuf_add(dst, src, len);
                src += len;
                while (need_bs_quote(*src)) {
                        strbuf_addstr(dst, "'\\");
                        strbuf_addch(dst, *src++);
                        strbuf_addch(dst, '\'');
                }
        }
        strbuf_addch(dst, '\'');
        free(to_free);
}

void sq_quote_print(FILE *stream, const char *src)
{
        char c;

        fputc('\'', stream);
        while ((c = *src++)) {
                if (need_bs_quote(c)) {
                        fputs("'\\", stream);
                        fputc(c, stream);
                        fputc('\'', stream);
                } else {
                        fputc(c, stream);
                }
        }
        fputc('\'', stream);
}

void sq_quote_argv(struct strbuf *dst, const char** argv, size_t maxlen)
{
        int i;

        /* Copy into destination buffer. */
        strbuf_grow(dst, 255);
        for (i = 0; argv[i]; ++i) {
                strbuf_addch(dst, ' ');
                sq_quote_buf(dst, argv[i]);
                if (maxlen && dst->len > maxlen)
                        die("Too many or long arguments");
        }
}

static char *sq_dequote_step(char *arg, char **next)
{
        char *dst = arg;
        char *src = arg;
        char c;

        if (*src != '\'')
                return NULL;
        for (;;) {
                c = *++src;
                if (!c)
                        return NULL;
                if (c != '\'') {
                        *dst++ = c;
                        continue;
                }
                /* We stepped out of sq */
                switch (*++src) {
                case '\0':
                        *dst = 0;
                        if (next)
                                *next = NULL;
                        return arg;
                case '\\':
                        c = *++src;
                        if (need_bs_quote(c) && *++src == '\'') {
                                *dst++ = c;
                                continue;
                        }
                /* Fallthrough */
                default:
                        if (!next || !isspace(*src))
                                return NULL;
                        do {
                                c = *++src;
                        } while (isspace(c));
                        *dst = 0;
                        *next = src;
                        return arg;
                }
        }
}

char *sq_dequote(char *arg)
{
        return sq_dequote_step(arg, NULL);
}

int sq_dequote_to_argv(char *arg, const char ***argv, int *nr, int *alloc)
{
        char *next = arg;

        if (!*arg)
                return 0;
        do {
                char *dequoted = sq_dequote_step(next, &next);
                if (!dequoted)
                        return -1;
                ALLOC_GROW(*argv, *nr + 1, *alloc);
                (*argv)[(*nr)++] = dequoted;
        } while (next);

        return 0;
}

/* 1 means: quote as octal
 * 0 means: quote as octal if (quote_path_fully)
 * -1 means: never quote
 * c: quote as "\\c"
 */
#define X8(x)   x, x, x, x, x, x, x, x
#define X16(x)  X8(x), X8(x)
static signed char const sq_lookup[256] = {
        /*           0    1    2    3    4    5    6    7 */
        /* 0x00 */   1,   1,   1,   1,   1,   1,   1, 'a',
        /* 0x08 */ 'b', 't', 'n', 'v', 'f', 'r',   1,   1,
        /* 0x10 */ X16(1),
        /* 0x20 */  -1,  -1, '"',  -1,  -1,  -1,  -1,  -1,
        /* 0x28 */ X16(-1), X16(-1), X16(-1),
        /* 0x58 */  -1,  -1,  -1,  -1,'\\',  -1,  -1,  -1,
        /* 0x60 */ X16(-1), X8(-1),
        /* 0x78 */  -1,  -1,  -1,  -1,  -1,  -1,  -1,   1,
        /* 0x80 */ /* set to 0 */
};

static inline int sq_must_quote(char c)
{
        return sq_lookup[(unsigned char)c] + quote_path_fully > 0;
}

/* returns the longest prefix not needing a quote up to maxlen if positive.
   This stops at the first \0 because it's marked as a character needing an
   escape */
static size_t next_quote_pos(const char *s, ssize_t maxlen)
{
        size_t len;
        if (maxlen < 0) {
                for (len = 0; !sq_must_quote(s[len]); len++);
        } else {
                for (len = 0; len < maxlen && !sq_must_quote(s[len]); len++);
        }
        return len;
}

/*
 * C-style name quoting.
 *
 * (1) if sb and fp are both NULL, inspect the input name and counts the
 *     number of bytes that are needed to hold c_style quoted version of name,
 *     counting the double quotes around it but not terminating NUL, and
 *     returns it.
 *     However, if name does not need c_style quoting, it returns 0.
 *
 * (2) if sb or fp are not NULL, it emits the c_style quoted version
 *     of name, enclosed with double quotes if asked and needed only.
 *     Return value is the same as in (1).
 */
static size_t quote_c_style_counted(const char *name, ssize_t maxlen,
                                    struct strbuf *sb, FILE *fp, int no_dq)
{
#undef EMIT
#define EMIT(c)                                 \
        do {                                        \
                if (sb) strbuf_addch(sb, (c));          \
                if (fp) fputc((c), fp);                 \
                count++;                                \
        } while (0)
#define EMITBUF(s, l)                           \
        do {                                        \
                if (sb) strbuf_add(sb, (s), (l));       \
                if (fp) fwrite((s), (l), 1, fp);        \
                count += (l);                           \
        } while (0)

        size_t len, count = 0;
        const char *p = name;

        for (;;) {
                int ch;

                len = next_quote_pos(p, maxlen);
                if (len == maxlen || (maxlen < 0 && !p[len]))
                        break;

                if (!no_dq && p == name)
                        EMIT('"');

                EMITBUF(p, len);
                EMIT('\\');
                p += len;
                ch = (unsigned char)*p++;
                if (maxlen >= 0)
                        maxlen -= len + 1;
                if (sq_lookup[ch] >= ' ') {
                        EMIT(sq_lookup[ch]);
                } else {
                        EMIT(((ch >> 6) & 03) + '0');
                        EMIT(((ch >> 3) & 07) + '0');
                        EMIT(((ch >> 0) & 07) + '0');
                }
        }

        EMITBUF(p, len);
        if (p == name)   /* no ending quote needed */
                return 0;

        if (!no_dq)
                EMIT('"');
        return count;
}

size_t quote_c_style(const char *name, struct strbuf *sb, FILE *fp, int nodq)
{
        return quote_c_style_counted(name, -1, sb, fp, nodq);
}

void quote_two_c_style(struct strbuf *sb, const char *prefix, const char *path, int nodq)
{
        if (quote_c_style(prefix, NULL, NULL, 0) ||
            quote_c_style(path, NULL, NULL, 0)) {
                if (!nodq)
                        strbuf_addch(sb, '"');
                quote_c_style(prefix, sb, NULL, 1);
                quote_c_style(path, sb, NULL, 1);
                if (!nodq)
                        strbuf_addch(sb, '"');
        } else {
                strbuf_addstr(sb, prefix);
                strbuf_addstr(sb, path);
        }
}

void write_name_quoted(const char *name, FILE *fp, int terminator)
{
        if (terminator) {
                quote_c_style(name, NULL, fp, 0);
        } else {
                fputs(name, fp);
        }
        fputc(terminator, fp);
}

void write_name_quotedpfx(const char *pfx, size_t pfxlen,
                          const char *name, FILE *fp, int terminator)
{
        int needquote = 0;

        if (terminator) {
                needquote = next_quote_pos(pfx, pfxlen) < pfxlen
                        || name[next_quote_pos(name, -1)];
        }
        if (needquote) {
                fputc('"', fp);
                quote_c_style_counted(pfx, pfxlen, NULL, fp, 1);
                quote_c_style(name, NULL, fp, 1);
                fputc('"', fp);
        } else {
                fwrite(pfx, pfxlen, 1, fp);
                fputs(name, fp);
        }
        fputc(terminator, fp);
}

/* quote path as relative to the given prefix */
char *quote_path_relative(const char *in, int len,
                          struct strbuf *out, const char *prefix)
{
        int needquote;

        if (len < 0)
                len = strlen(in);

        /* "../" prefix itself does not need quoting, but "in" might. */
        needquote = next_quote_pos(in, len) < len;
        strbuf_setlen(out, 0);
        strbuf_grow(out, len);

        if (needquote)
                strbuf_addch(out, '"');
        if (prefix) {
                int off = 0;
                while (prefix[off] && off < len && prefix[off] == in[off])
                        if (prefix[off] == '/') {
                                prefix += off + 1;
                                in += off + 1;
                                len -= off + 1;
                                off = 0;
                        } else
                                off++;

                for (; *prefix; prefix++)
                        if (*prefix == '/')
                                strbuf_addstr(out, "../");
        }

        quote_c_style_counted (in, len, out, NULL, 1);

        if (needquote)
                strbuf_addch(out, '"');
        if (!out->len)
                strbuf_addstr(out, "./");

        return out->buf;
}

/*
 * C-style name unquoting.
 *
 * Quoted should point at the opening double quote.
 * + Returns 0 if it was able to unquote the string properly, and appends the
 *   result in the strbuf `sb'.
 * + Returns -1 in case of error, and doesn't touch the strbuf. Though note
 *   that this function will allocate memory in the strbuf, so calling
 *   strbuf_release is mandatory whichever result unquote_c_style returns.
 *
 * Updates endp pointer to point at one past the ending double quote if given.
 */
int unquote_c_style(struct strbuf *sb, const char *quoted, const char **endp)
{
        size_t oldlen = sb->len, len;
        int ch, ac;

        if (*quoted++ != '"')
                return -1;

        for (;;) {
                len = strcspn(quoted, "\"\\");
                strbuf_add(sb, quoted, len);
                quoted += len;

                switch (*quoted++) {
                  case '"':
                        if (endp)
                                *endp = quoted;
                        return 0;
                  case '\\':
                        break;
                  default:
                        goto error;
                }

                switch ((ch = *quoted++)) {
                case 'a': ch = '\a'; break;
                case 'b': ch = '\b'; break;
                case 'f': ch = '\f'; break;
                case 'n': ch = '\n'; break;
                case 'r': ch = '\r'; break;
                case 't': ch = '\t'; break;
                case 'v': ch = '\v'; break;

                case '\\': case '"':
                        break; /* verbatim */

                /* octal values with first digit over 4 overflow */
                case '0': case '1': case '2': case '3':
                                        ac = ((ch - '0') << 6);
                        if ((ch = *quoted++) < '0' || '7' < ch)
                                goto error;
                                        ac |= ((ch - '0') << 3);
                        if ((ch = *quoted++) < '0' || '7' < ch)
                                goto error;
                                        ac |= (ch - '0');
                                        ch = ac;
                                        break;
                                default:
                        goto error;
                        }
                strbuf_addch(sb, ch);
                }

  error:
        strbuf_setlen(sb, oldlen);
        return -1;
}

/* quoting as a string literal for other languages */

void perl_quote_print(FILE *stream, const char *src)
{
        const char sq = '\'';
        const char bq = '\\';
        char c;

        fputc(sq, stream);
        while ((c = *src++)) {
                if (c == sq || c == bq)
                        fputc(bq, stream);
                fputc(c, stream);
        }
        fputc(sq, stream);
}

void python_quote_print(FILE *stream, const char *src)
{
        const char sq = '\'';
        const char bq = '\\';
        const char nl = '\n';
        char c;

        fputc(sq, stream);
        while ((c = *src++)) {
                if (c == nl) {
                        fputc(bq, stream);
                        fputc('n', stream);
                        continue;
                }
                if (c == sq || c == bq)
                        fputc(bq, stream);
                fputc(c, stream);
        }
        fputc(sq, stream);
}

void tcl_quote_print(FILE *stream, const char *src)
{
        char c;

        fputc('"', stream);
        while ((c = *src++)) {
                switch (c) {
                case '[': case ']':
                case '{': case '}':
                case '$': case '\\': case '"':
                        fputc('\\', stream);
                default:
                        fputc(c, stream);
                        break;
                case '\f':
                        fputs("\\f", stream);
                        break;
                case '\r':
                        fputs("\\r", stream);
                        break;
                case '\n':
                        fputs("\\n", stream);
                        break;
                case '\t':
                        fputs("\\t", stream);
                        break;
                case '\v':
                        fputs("\\v", stream);
                        break;
                }
        }
        fputc('"', stream);
}