test-ellipsize: add tests for ellipsize_mem, fix bugs

First, ellipsize() and ellipsize_mem() should not read past the input
buffer. Those functions take an explicit length for the input data, so they
should not assume that the buffer is terminated by a nul.

Second, ellipsization was off in various cases where wide on multi-byte
characters were used.

We had some basic test for ellipsize(), but apparently it wasn't enough to
catch more serious cases.

Should fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=8686.

4 files changed, 129 insertions, 32 deletions

diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index 882683c767..a9362bf8bd 100644
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -469,8 +469,8 @@ static int write_ellipsis(char *buf, bool unicode) {
 }
 
 static char *ascii_ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigned percent) {
-        size_t x, need_space;
-        char *r;
+        size_t x, need_space, suffix_len;
+        char *t;
 
         assert(s);
         assert(percent <= 100);
@@ -506,8 +506,8 @@ static char *ascii_ellipsize_mem(const char *s, size_t old_length, size_t new_le
          * either for the UTF-8 encoded character or for three ASCII characters. */
         need_space = is_locale_utf8() ? 1 : 3;
 
-        r = new(char, new_length+3);
-        if (!r)
+        t = new(char, new_length+3);
+        if (!t)
                 return NULL;
 
         assert(new_length >= need_space);
@@ -515,13 +515,13 @@ static char *ascii_ellipsize_mem(const char *s, size_t old_length, size_t new_le
         x = ((new_length - need_space) * percent + 50) / 100;
         assert(x <= new_length - need_space);
 
-        memcpy(r, s, x);
-        write_ellipsis(r + x, false);
-        memcpy(r + x + 3,
-               s + old_length - (new_length - x - need_space),
-               new_length - x - need_space + 1);
+        memcpy(t, s, x);
+        write_ellipsis(t + x, false);
+        suffix_len = new_length - x - need_space;
+        memcpy(t + x + 3, s + old_length - suffix_len, suffix_len);
+        *(t + x + 3 + suffix_len) = '\0';
 
-        return r;
+        return t;
 }
 
 char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigned percent) {
@@ -559,35 +559,49 @@ char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigne
         assert(x <= new_length - 1);
 
         k = 0;
-        for (i = s; k < x && i < s + old_length; i = utf8_next_char(i)) {
+        for (i = s; i < s + old_length; i = utf8_next_char(i)) {
                 char32_t c;
+                int w;
 
                 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++;
+                w = unichar_iswide(c) ? 2 : 1;
+                if (k + w <= x)
+                        k += w;
+                else
+                        break;
+        }
 
-        for (j = s + old_length; k < new_length && j > i; ) {
+        for (j = s + old_length; j > i; ) {
                 char32_t c;
+                int w;
+                const char *jj;
 
-                j = utf8_prev_char(j);
-                r = utf8_encoded_to_unichar(j, &c);
+                jj = utf8_prev_char(j);
+                r = utf8_encoded_to_unichar(jj, &c);
                 if (r < 0)
                         return NULL;
-                k += unichar_iswide(c) ? 2 : 1;
+
+                w = unichar_iswide(c) ? 2 : 1;
+                if (k + w <= new_length) {
+                        k += w;
+                        j = jj;
+                } else
+                        break;
         }
         assert(i <= j);
 
         /* we don't actually need to ellipsize */
         if (i == j)
-                return memdup(s, old_length + 1);
+                return memdup_suffix0(s, old_length);
 
-        /* make space for ellipsis */
-        j = utf8_next_char(j);
+        /* make space for ellipsis, if possible */
+        if (j < s + old_length)
+                j = utf8_next_char(j);
+        else if (i > s)
+                i = utf8_prev_char(i);
 
         len = i - s;
         len2 = s + old_length - j;
@@ -602,7 +616,8 @@ char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigne
 
         memcpy(e, s, len);
         write_ellipsis(e + len, true);
-        memcpy(e + len + 3, j, len2 + 1);
+        memcpy(e + len + 3, j, len2);
+        *(e + len + 3 + len2) = '\0';
 
         return e;
 }
diff --git a/src/test/test-ellipsize.c b/src/test/test-ellipsize.c
index 902bc3342f..7d6b2b5449 100644
--- a/src/test/test-ellipsize.c
+++ b/src/test/test-ellipsize.c
@@ -10,10 +10,80 @@
 #include "alloc-util.h"
 #include "def.h"
 #include "string-util.h"
+#include "strv.h"
 #include "terminal-util.h"
 #include "util.h"
+#include "utf8.h"
 
-static void test_one(const char *p) {
+static void test_ellipsize_mem_one(const char *s, size_t old_length, size_t new_length) {
+        _cleanup_free_ char *n = NULL;
+        _cleanup_free_ char *t1 = NULL, *t2 = NULL, *t3 = NULL;
+        char buf[LINE_MAX];
+        bool has_wide_chars;
+        size_t max_width;
+
+        n = memdup_suffix0(s, old_length);
+
+        if (!utf8_is_valid(n))
+                /* We don't support invalid sequences… */
+                return;
+
+        /* Report out inputs. We duplicate the data so that cellescape
+         * can properly report truncated multibyte sequences. */
+        log_info("%s \"%s\" old_length=%zu/%zu new_length=%zu", __func__,
+                 cellescape(buf, sizeof buf, n),
+                 old_length, utf8_console_width(n),
+                 new_length);
+
+        /* To keep this test simple, any case with wide chars starts with this glyph */
+        has_wide_chars = startswith(s, "你");
+        max_width = MIN(utf8_console_width(n), new_length);
+
+        t1 = ellipsize_mem(n, old_length, new_length, 30);
+        log_info("30%% → %s utf8_console_width=%zu", t1, utf8_console_width(t1));
+        if (!has_wide_chars)
+                assert_se(utf8_console_width(t1) == max_width);
+        else
+                assert_se(utf8_console_width(t1) <= max_width);
+
+        t2 = ellipsize_mem(n, old_length, new_length, 90);
+        log_info("90%% → %s utf8_console_width=%zu", t2, utf8_console_width(t2));
+        if (!has_wide_chars)
+                assert_se(utf8_console_width(t2) == max_width);
+        else
+                assert_se(utf8_console_width(t2) <= max_width);
+
+        t3 = ellipsize_mem(n, old_length, new_length, 100);
+        log_info("100%% → %s utf8_console_width=%zu", t3, utf8_console_width(t3));
+        if (!has_wide_chars)
+                assert_se(utf8_console_width(t3) == max_width);
+        else
+                assert_se(utf8_console_width(t3) <= max_width);
+
+        if (new_length >= old_length) {
+                assert_se(streq(t1, n));
+                assert_se(streq(t2, n));
+                assert_se(streq(t3, n));
+        }
+}
+
+static void test_ellipsize_mem(void) {
+        const char *s;
+        ssize_t l, k;
+
+        FOREACH_STRING(s,
+                       "_XXXXXXXXXXX_", /* ASCII */
+                       "_aąęółśćńżźć_", /* two-byte utf-8 */
+                       "გამარჯობა",     /* multi-byte utf-8 */
+                       "你好世界",       /* wide characters */
+                       "你გą世óoó界")    /* a mix */
+
+                for (l = strlen(s); l >= 0; l--)
+                        for (k = strlen(s) + 1; k >= 0; k--)
+                                test_ellipsize_mem_one(s, l, k);
+}
+
+static void test_ellipsize_one(const char *p) {
         _cleanup_free_ char *t;
         t = ellipsize(p, columns(), 70);
         puts(t);
@@ -43,15 +113,20 @@ static void test_one(const char *p) {
         puts(t);
 }
 
+static void test_ellipsize(void) {
+        test_ellipsize_one(DIGITS LETTERS DIGITS LETTERS);
+        test_ellipsize_one("한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어");
+        test_ellipsize_one("-日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国");
+        test_ellipsize_one("中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国-中国中国中国中国中国中国中国中国中国中国中国中国中国");
+        test_ellipsize_one("sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd");
+        test_ellipsize_one("🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮");
+        test_ellipsize_one("Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.");
+        test_ellipsize_one("shórt");
+}
+
 int main(int argc, char *argv[]) {
-        test_one(DIGITS LETTERS DIGITS LETTERS);
-        test_one("한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어한국어");
-        test_one("-日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国日本国");
-        test_one("中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国中国-中国中国中国中国中国中国中国中国中国中国中国中国中国");
-        test_one("sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd sÿstëmd");
-        test_one("🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮🐮");
-        test_one("Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.");
-        test_one("shórt");
+        test_ellipsize_mem();
+        test_ellipsize();
 
         return 0;
 }
diff --git a/src/test/test-string-util.c b/src/test/test-string-util.c
index 8b176781de..d6eca393ee 100644
--- a/src/test/test-string-util.c
+++ b/src/test/test-string-util.c
@@ -10,6 +10,7 @@
 #include "macro.h"
 #include "string-util.h"
 #include "strv.h"
+#include "utf8.h"
 
 static void test_string_erase(void) {
         char *x;
diff --git a/test/fuzz-regressions/fuzz-journal-remote/oss-fuzz-8686 b/test/fuzz-regressions/fuzz-journal-remote/oss-fuzz-8686
new file mode 100644
index 0000000000..7c73c8cd9b
--- /dev/null
+++ b/test/fuzz-regressions/fuzz-journal-remote/oss-fuzz-8686
@@ -0,0 +1,6 @@
+__REALTIME_TIMESTAMP=  6
+SYSLOG_IDENTIFIER=             
+MESSAGE=                        ᅟ                                                                                                                                                                                                                                                                                
+SYSLOG_PID=            
+
+  
\ No newline at end of file