src/basic/string-util.c

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include "alloc-util.h"
#include "gunicode.h"
#include "macro.h"
#include "string-util.h"
#include "utf8.h"
#include "util.h"

int strcmp_ptr(const char *a, const char *b) {

        /* Like strcmp(), but tries to make sense of NULL pointers */
        if (a && b)
                return strcmp(a, b);

        if (!a && b)
                return -1;

        if (a && !b)
                return 1;

        return 0;
}

char* endswith(const char *s, const char *postfix) {
        size_t sl, pl;

        assert(s);
        assert(postfix);

        sl = strlen(s);
        pl = strlen(postfix);

        if (pl == 0)
                return (char*) s + sl;

        if (sl < pl)
                return NULL;

        if (memcmp(s + sl - pl, postfix, pl) != 0)
                return NULL;

        return (char*) s + sl - pl;
}

char* endswith_no_case(const char *s, const char *postfix) {
        size_t sl, pl;

        assert(s);
        assert(postfix);

        sl = strlen(s);
        pl = strlen(postfix);

        if (pl == 0)
                return (char*) s + sl;

        if (sl < pl)
                return NULL;

        if (strcasecmp(s + sl - pl, postfix) != 0)
                return NULL;

        return (char*) s + sl - pl;
}

char* first_word(const char *s, const char *word) {
        size_t sl, wl;
        const char *p;

        assert(s);
        assert(word);

        /* Checks if the string starts with the specified word, either
         * followed by NUL or by whitespace. Returns a pointer to the
         * NUL or the first character after the whitespace. */

        sl = strlen(s);
        wl = strlen(word);

        if (sl < wl)
                return NULL;

        if (wl == 0)
                return (char*) s;

        if (memcmp(s, word, wl) != 0)
                return NULL;

        p = s + wl;
        if (*p == 0)
                return (char*) p;

        if (!strchr(WHITESPACE, *p))
                return NULL;

        p += strspn(p, WHITESPACE);
        return (char*) p;
}

static size_t strcspn_escaped(const char *s, const char *reject) {
        bool escaped = false;
        int n;

        for (n=0; s[n]; n++) {
                if (escaped)
                        escaped = false;
                else if (s[n] == '\\')
                        escaped = true;
                else if (strchr(reject, s[n]))
                        break;
        }

        /* if s ends in \, return index of previous char */
        return n - escaped;
}

/* Split a string into words. */
const char* split(const char **state, size_t *l, const char *separator, bool quoted) {
        const char *current;

        current = *state;

        if (!*current) {
                assert(**state == '\0');
                return NULL;
        }

        current += strspn(current, separator);
        if (!*current) {
                *state = current;
                return NULL;
        }

        if (quoted && strchr("\'\"", *current)) {
                char quotechars[2] = {*current, '\0'};

                *l = strcspn_escaped(current + 1, quotechars);
                if (current[*l + 1] == '\0' || current[*l + 1] != quotechars[0] ||
                    (current[*l + 2] && !strchr(separator, current[*l + 2]))) {
                        /* right quote missing or garbage at the end */
                        *state = current;
                        return NULL;
                }
                *state = current++ + *l + 2;
        } else if (quoted) {
                *l = strcspn_escaped(current, separator);
                if (current[*l] && !strchr(separator, current[*l])) {
                        /* unfinished escape */
                        *state = current;
                        return NULL;
                }
                *state = current + *l;
        } else {
                *l = strcspn(current, separator);
                *state = current + *l;
        }

        return current;
}

char *strnappend(const char *s, const char *suffix, size_t b) {
        size_t a;
        char *r;

        if (!s && !suffix)
                return strdup("");

        if (!s)
                return strndup(suffix, b);

        if (!suffix)
                return strdup(s);

        assert(s);
        assert(suffix);

        a = strlen(s);
        if (b > ((size_t) -1) - a)
                return NULL;

        r = new(char, a+b+1);
        if (!r)
                return NULL;

        memcpy(r, s, a);
        memcpy(r+a, suffix, b);
        r[a+b] = 0;

        return r;
}

char *strappend(const char *s, const char *suffix) {
        return strnappend(s, suffix, suffix ? strlen(suffix) : 0);
}

char *strjoin(const char *x, ...) {
        va_list ap;
        size_t l;
        char *r, *p;

        va_start(ap, x);

        if (x) {
                l = strlen(x);

                for (;;) {
                        const char *t;
                        size_t n;

                        t = va_arg(ap, const char *);
                        if (!t)
                                break;

                        n = strlen(t);
                        if (n > ((size_t) -1) - l) {
                                va_end(ap);
                                return NULL;
                        }

                        l += n;
                }
        } else
                l = 0;

        va_end(ap);

        r = new(char, l+1);
        if (!r)
                return NULL;

        if (x) {
                p = stpcpy(r, x);

                va_start(ap, x);

                for (;;) {
                        const char *t;

                        t = va_arg(ap, const char *);
                        if (!t)
                                break;

                        p = stpcpy(p, t);
                }

                va_end(ap);
        } else
                r[0] = 0;

        return r;
}

char *strstrip(char *s) {
        char *e;

        /* Drops trailing whitespace. Modifies the string in
         * place. Returns pointer to first non-space character */

        s += strspn(s, WHITESPACE);

        for (e = strchr(s, 0); e > s; e --)
                if (!strchr(WHITESPACE, e[-1]))
                        break;

        *e = 0;

        return s;
}

char *delete_chars(char *s, const char *bad) {
        char *f, *t;

        /* Drops all whitespace, regardless where in the string */

        for (f = s, t = s; *f; f++) {
                if (strchr(bad, *f))
                        continue;

                *(t++) = *f;
        }

        *t = 0;

        return s;
}

char *truncate_nl(char *s) {
        assert(s);

        s[strcspn(s, NEWLINE)] = 0;
        return s;
}

char ascii_tolower(char x) {

        if (x >= 'A' && x <= 'Z')
                return x - 'A' + 'a';

        return x;
}

char *ascii_strlower(char *t) {
        char *p;

        assert(t);

        for (p = t; *p; p++)
                *p = ascii_tolower(*p);

        return t;
}

char *ascii_strlower_n(char *t, size_t n) {
        size_t i;

        if (n <= 0)
                return t;

        for (i = 0; i < n; i++)
                t[i] = ascii_tolower(t[i]);

        return t;
}

int ascii_strcasecmp_n(const char *a, const char *b, size_t n) {

        for (; n > 0; a++, b++, n--) {
                int x, y;

                x = (int) (uint8_t) ascii_tolower(*a);
                y = (int) (uint8_t) ascii_tolower(*b);

                if (x != y)
                        return x - y;
        }

        return 0;
}

int ascii_strcasecmp_nn(const char *a, size_t n, const char *b, size_t m) {
        int r;

        r = ascii_strcasecmp_n(a, b, MIN(n, m));
        if (r != 0)
                return r;

        if (n < m)
                return -1;
        else if (n > m)
                return 1;
        else
                return 0;
}

bool chars_intersect(const char *a, const char *b) {
        const char *p;

        /* Returns true if any of the chars in a are in b. */
        for (p = a; *p; p++)
                if (strchr(b, *p))
                        return true;

        return false;
}

bool string_has_cc(const char *p, const char *ok) {
        const char *t;

        assert(p);

        /*
         * Check if a string contains control characters. If 'ok' is
         * non-NULL it may be a string containing additional CCs to be
         * considered OK.
         */

        for (t = p; *t; t++) {
                if (ok && strchr(ok, *t))
                        continue;

                if (*t > 0 && *t < ' ')
                        return true;

                if (*t == 127)
                        return true;
        }

        return false;
}

static char *ascii_ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigned percent) {
        size_t x;
        char *r;

        assert(s);
        assert(percent <= 100);
        assert(new_length >= 3);

        if (old_length <= 3 || old_length <= new_length)
                return strndup(s, old_length);

        r = new0(char, new_length+1);
        if (!r)
                return NULL;

        x = (new_length * percent) / 100;

        if (x > new_length - 3)
                x = new_length - 3;

        memcpy(r, s, x);
        r[x] = '.';
        r[x+1] = '.';
        r[x+2] = '.';
        memcpy(r + x + 3,
               s + old_length - (new_length - x - 3),
               new_length - x - 3);

        return r;
}

char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigned percent) {
        size_t x;
        char *e;
        const char *i, *j;
        unsigned k, len, len2;
        int r;

        assert(s);
        assert(percent <= 100);
        assert(new_length >= 3);

        /* if no multibyte characters use ascii_ellipsize_mem for speed */
        if (ascii_is_valid(s))
                return ascii_ellipsize_mem(s, old_length, new_length, percent);

        if (old_length <= 3 || old_length <= new_length)
                return strndup(s, old_length);

        x = (new_length * percent) / 100;

        if (x > new_length - 3)
                x = new_length - 3;

        k = 0;
        for (i = s; k < x && i < s + old_length; i = utf8_next_char(i)) {
                char32_t c;

                r = utf8_encoded_to_unichar(i, &c);
                if (r < 0)
                        return NULL;
                k += unichar_iswide(c) ? 2 : 1;
        }

        if (k > x) /* last character was wide and went over quota */
                x++;

        for (j = s + old_length; k < new_length && j > i; ) {
                char32_t c;

                j = utf8_prev_char(j);
                r = utf8_encoded_to_unichar(j, &c);
                if (r < 0)
                        return NULL;
                k += unichar_iswide(c) ? 2 : 1;
        }
        assert(i <= j);

        /* we don't actually need to ellipsize */
        if (i == j)
                return memdup(s, old_length + 1);

        /* make space for ellipsis */
        j = utf8_next_char(j);

        len = i - s;
        len2 = s + old_length - j;
        e = new(char, len + 3 + len2 + 1);
        if (!e)
                return NULL;

        /*
        printf("old_length=%zu new_length=%zu x=%zu len=%u len2=%u k=%u\n",
               old_length, new_length, x, len, len2, k);
        */

        memcpy(e, s, len);
        e[len]   = 0xe2; /* tri-dot ellipsis: … */
        e[len + 1] = 0x80;
        e[len + 2] = 0xa6;

        memcpy(e + len + 3, j, len2 + 1);

        return e;
}

char *ellipsize(const char *s, size_t length, unsigned percent) {
        return ellipsize_mem(s, strlen(s), length, percent);
}

bool nulstr_contains(const char*nulstr, const char *needle) {
        const char *i;

        if (!nulstr)
                return false;

        NULSTR_FOREACH(i, nulstr)
                if (streq(i, needle))
                        return true;

        return false;
}

char* strshorten(char *s, size_t l) {
        assert(s);

        if (l < strlen(s))
                s[l] = 0;

        return s;
}

char *strreplace(const char *text, const char *old_string, const char *new_string) {
        const char *f;
        char *t, *r;
        size_t l, old_len, new_len;

        assert(text);
        assert(old_string);
        assert(new_string);

        old_len = strlen(old_string);
        new_len = strlen(new_string);

        l = strlen(text);
        r = new(char, l+1);
        if (!r)
                return NULL;

        f = text;
        t = r;
        while (*f) {
                char *a;
                size_t d, nl;

                if (!startswith(f, old_string)) {
                        *(t++) = *(f++);
                        continue;
                }

                d = t - r;
                nl = l - old_len + new_len;
                a = realloc(r, nl + 1);
                if (!a)
                        goto oom;

                l = nl;
                r = a;
                t = r + d;

                t = stpcpy(t, new_string);
                f += old_len;
        }

        *t = 0;
        return r;

oom:
        free(r);
        return NULL;
}

char *strip_tab_ansi(char **ibuf, size_t *_isz) {
        const char *i, *begin = NULL;
        enum {
                STATE_OTHER,
                STATE_ESCAPE,
                STATE_BRACKET
        } state = STATE_OTHER;
        char *obuf = NULL;
        size_t osz = 0, isz;
        FILE *f;

        assert(ibuf);
        assert(*ibuf);

        /* Strips ANSI color and replaces TABs by 8 spaces */

        isz = _isz ? *_isz : strlen(*ibuf);

        f = open_memstream(&obuf, &osz);
        if (!f)
                return NULL;

        for (i = *ibuf; i < *ibuf + isz + 1; i++) {

                switch (state) {

                case STATE_OTHER:
                        if (i >= *ibuf + isz) /* EOT */
                                break;
                        else if (*i == '\x1B')
                                state = STATE_ESCAPE;
                        else if (*i == '\t')
                                fputs("        ", f);
                        else
                                fputc(*i, f);
                        break;

                case STATE_ESCAPE:
                        if (i >= *ibuf + isz) { /* EOT */
                                fputc('\x1B', f);
                                break;
                        } else if (*i == '[') {
                                state = STATE_BRACKET;
                                begin = i + 1;
                        } else {
                                fputc('\x1B', f);
                                fputc(*i, f);
                                state = STATE_OTHER;
                        }

                        break;

                case STATE_BRACKET:

                        if (i >= *ibuf + isz || /* EOT */
                            (!(*i >= '0' && *i <= '9') && *i != ';' && *i != 'm')) {
                                fputc('\x1B', f);
                                fputc('[', f);
                                state = STATE_OTHER;
                                i = begin-1;
                        } else if (*i == 'm')
                                state = STATE_OTHER;
                        break;
                }
        }

        if (ferror(f)) {
                fclose(f);
                free(obuf);
                return NULL;
        }

        fclose(f);

        free(*ibuf);
        *ibuf = obuf;

        if (_isz)
                *_isz = osz;

        return obuf;
}

char *strextend(char **x, ...) {
        va_list ap;
        size_t f, l;
        char *r, *p;

        assert(x);

        l = f = *x ? strlen(*x) : 0;

        va_start(ap, x);
        for (;;) {
                const char *t;
                size_t n;

                t = va_arg(ap, const char *);
                if (!t)
                        break;

                n = strlen(t);
                if (n > ((size_t) -1) - l) {
                        va_end(ap);
                        return NULL;
                }

                l += n;
        }
        va_end(ap);

        r = realloc(*x, l+1);
        if (!r)
                return NULL;

        p = r + f;

        va_start(ap, x);
        for (;;) {
                const char *t;

                t = va_arg(ap, const char *);
                if (!t)
                        break;

                p = stpcpy(p, t);
        }
        va_end(ap);

        *p = 0;
        *x = r;

        return r + l;
}

char *strrep(const char *s, unsigned n) {
        size_t l;
        char *r, *p;
        unsigned i;

        assert(s);

        l = strlen(s);
        p = r = malloc(l * n + 1);
        if (!r)
                return NULL;

        for (i = 0; i < n; i++)
                p = stpcpy(p, s);

        *p = 0;
        return r;
}

int split_pair(const char *s, const char *sep, char **l, char **r) {
        char *x, *a, *b;

        assert(s);
        assert(sep);
        assert(l);
        assert(r);

        if (isempty(sep))
                return -EINVAL;

        x = strstr(s, sep);
        if (!x)
                return -EINVAL;

        a = strndup(s, x - s);
        if (!a)
                return -ENOMEM;

        b = strdup(x + strlen(sep));
        if (!b) {
                free(a);
                return -ENOMEM;
        }

        *l = a;
        *r = b;

        return 0;
}

int free_and_strdup(char **p, const char *s) {
        char *t;

        assert(p);

        /* Replaces a string pointer with an strdup()ed new string,
         * possibly freeing the old one. */

        if (streq_ptr(*p, s))
                return 0;

        if (s) {
                t = strdup(s);
                if (!t)
                        return -ENOMEM;
        } else
                t = NULL;

        free(*p);
        *p = t;

        return 1;
}

#pragma GCC push_options
#pragma GCC optimize("O0")

void* memory_erase(void *p, size_t l) {
        volatile uint8_t* x = (volatile uint8_t*) p;

        /* This basically does what memset() does, but hopefully isn't
         * optimized away by the compiler. One of those days, when
         * glibc learns memset_s() we should replace this call by
         * memset_s(), but until then this has to do. */

        for (; l > 0; l--)
                *(x++) = 'x';

        return p;
}

#pragma GCC pop_options

char* string_erase(char *x) {

        if (!x)
                return NULL;

        /* A delicious drop of snake-oil! To be called on memory where
         * we stored passphrases or so, after we used them. */

        return memory_erase(x, strlen(x));
}

char *string_free_erase(char *s) {
        return mfree(string_erase(s));
}

bool string_is_safe(const char *p) {
        const char *t;

        if (!p)
                return false;

        for (t = p; *t; t++) {
                if (*t > 0 && *t < ' ') /* no control characters */
                        return false;

                if (strchr(QUOTES "\\\x7f", *t))
                        return false;
        }

        return true;
}