journalctl: add highlighting for matched substring

Red is used for highligting, the same as grep does. Except when the line is
highlighted red already, because it has high priority, in which case plain ansi
highlight is used for the matched substring.

Coloring is implemented for short and cat outputs, and not for other types.
I guess we could also add it for verbose output in the future.

1 files changed, 73 insertions, 17 deletions

diff --git a/src/shared/logs-show.c b/src/shared/logs-show.c
index a861be7b32..3d0be7ab00 100644
--- a/src/shared/logs-show.c
+++ b/src/shared/logs-show.c
@@ -166,8 +166,17 @@ static bool shall_print(const char *p, size_t l, OutputFlags flags) {
         return true;
 }
 
-static bool print_multiline(FILE *f, unsigned prefix, unsigned n_columns, OutputFlags flags, int priority, const char* message, size_t message_len) {
-        const char *color_on = "", *color_off = "";
+static bool print_multiline(
+                FILE *f,
+                unsigned prefix,
+                unsigned n_columns,
+                OutputFlags flags,
+                int priority,
+                const char* message,
+                size_t message_len,
+                size_t highlight[2]) {
+
+        const char *color_on = "", *color_off = "", *highlight_on = "";
         const char *pos, *end;
         bool ellipsized = false;
         int line = 0;
@@ -176,9 +185,11 @@ static bool print_multiline(FILE *f, unsigned prefix, unsigned n_columns, Output
                 if (priority <= LOG_ERR) {
                         color_on = ANSI_HIGHLIGHT_RED;
                         color_off = ANSI_NORMAL;
+                        highlight_on = ANSI_HIGHLIGHT;
                 } else if (priority <= LOG_NOTICE) {
                         color_on = ANSI_HIGHLIGHT;
                         color_off = ANSI_NORMAL;
+                        highlight_on = ANSI_HIGHLIGHT_RED;
                 }
         }
 
@@ -209,9 +220,28 @@ static bool print_multiline(FILE *f, unsigned prefix, unsigned n_columns, Output
 
                 if (flags & (OUTPUT_FULL_WIDTH | OUTPUT_SHOW_ALL) ||
                     (prefix + len + 1 < n_columns && !tail_line)) {
-                        fprintf(f, "%*s%s%.*s%s\n",
-                                continuation * prefix, "",
-                                color_on, len, pos, color_off);
+                        if (highlight &&
+                            (size_t) (pos - message) <= highlight[0] &&
+                            highlight[0] < (size_t) len) {
+
+                                fprintf(f, "%*s%s%.*s",
+                                        continuation * prefix, "",
+                                        color_on, (int) highlight[0], pos);
+                                fprintf(f, "%s%.*s",
+                                        highlight_on,
+                                        (int) (MIN((size_t) len, highlight[1]) - highlight[0]),
+                                        pos + highlight[0]);
+                                if ((size_t) len > highlight[1])
+                                        fprintf(f, "%s%.*s",
+                                                color_on,
+                                                (int) (len - highlight[1]),
+                                                pos + highlight[1]);
+                                fprintf(f, "%s\n", color_off);
+
+                        } else
+                                fprintf(f, "%*s%s%.*s%s\n",
+                                        continuation * prefix, "",
+                                        color_on, len, pos, color_off);
                         continue;
                 }
 
@@ -369,7 +399,8 @@ static int output_short(
                 OutputMode mode,
                 unsigned n_columns,
                 OutputFlags flags,
-                Set *output_fields) {
+                Set *output_fields,
+                size_t highlight[2]) {
 
         int r;
         const void *data;
@@ -390,6 +421,7 @@ static int output_short(
                 PARSE_FIELD_VEC_ENTRY("_SOURCE_REALTIME_TIMESTAMP=", &realtime, &realtime_len),
                 PARSE_FIELD_VEC_ENTRY("_SOURCE_MONOTONIC_TIMESTAMP=", &monotonic, &monotonic_len),
         };
+        size_t highlight_shifted[] = {highlight ? highlight[0] : 0, highlight ? highlight[1] : 0};
 
         assert(f);
         assert(j);
@@ -421,7 +453,7 @@ static int output_short(
         }
 
         if (!(flags & OUTPUT_SHOW_ALL))
-                strip_tab_ansi(&message, &message_len);
+                strip_tab_ansi(&message, &message_len, highlight_shifted);
 
         if (priority_len == 1 && *priority >= '0' && *priority <= '7')
                 p = *priority - '0';
@@ -468,7 +500,9 @@ static int output_short(
         } else {
                 fputs(": ", f);
                 ellipsized |=
-                        print_multiline(f, n + 2, n_columns, flags, p, message, message_len);
+                        print_multiline(f, n + 2, n_columns, flags, p,
+                                        message, message_len,
+                                        highlight_shifted);
         }
 
         if (flags & OUTPUT_CATALOG)
@@ -483,7 +517,8 @@ static int output_verbose(
                 OutputMode mode,
                 unsigned n_columns,
                 OutputFlags flags,
-                Set *output_fields) {
+                Set *output_fields,
+                size_t highlight[2]) {
 
         const void *data;
         size_t length;
@@ -561,7 +596,7 @@ static int output_verbose(
                     (((length < PRINT_CHAR_THRESHOLD) || flags & OUTPUT_FULL_WIDTH)
                      && utf8_is_printable(data, length))) {
                         fprintf(f, "    %s%.*s=", on, fieldlen, (const char*)data);
-                        print_multiline(f, 4 + fieldlen + 1, 0, OUTPUT_FULL_WIDTH, 0, c + 1, length - fieldlen - 1);
+                        print_multiline(f, 4 + fieldlen + 1, 0, OUTPUT_FULL_WIDTH, 0, c + 1, length - fieldlen - 1, NULL);
                         fputs(off, f);
                 } else {
                         char bytes[FORMAT_BYTES_MAX];
@@ -590,7 +625,8 @@ static int output_export(
                 OutputMode mode,
                 unsigned n_columns,
                 OutputFlags flags,
-                Set *output_fields) {
+                Set *output_fields,
+                size_t highlight[2]) {
 
         sd_id128_t boot_id;
         char sid[33];
@@ -728,7 +764,8 @@ static int output_json(
                 OutputMode mode,
                 unsigned n_columns,
                 OutputFlags flags,
-                Set *output_fields) {
+                Set *output_fields,
+                size_t highlight[2]) {
 
         uint64_t realtime, monotonic;
         _cleanup_free_ char *cursor = NULL;
@@ -952,15 +989,22 @@ static int output_cat(
                 OutputMode mode,
                 unsigned n_columns,
                 OutputFlags flags,
-                Set *output_fields) {
+                Set *output_fields,
+                size_t highlight[2]) {
 
         const void *data;
         size_t l;
         int r;
+        const char *highlight_on = "", *highlight_off = "";
 
         assert(j);
         assert(f);
 
+        if (flags & OUTPUT_COLOR) {
+                highlight_on = ANSI_HIGHLIGHT_RED;
+                highlight_off = ANSI_NORMAL;
+        }
+
         sd_journal_set_data_threshold(j, 0);
 
         r = sd_journal_get_data(j, "MESSAGE", &data, &l);
@@ -974,7 +1018,17 @@ static int output_cat(
 
         assert(l >= 8);
 
-        fwrite((const char*) data + 8, 1, l - 8, f);
+        if (highlight && (flags & OUTPUT_COLOR)) {
+                assert(highlight[0] <= highlight[1]);
+                assert(highlight[1] <= l - 8);
+
+                fwrite((const char*) data + 8, 1, highlight[0], f);
+                fwrite(highlight_on, 1, strlen(highlight_on), f);
+                fwrite((const char*) data + 8 + highlight[0], 1, highlight[1] - highlight[0], f);
+                fwrite(highlight_off, 1, strlen(highlight_off), f);
+                fwrite((const char*) data + 8 + highlight[1], 1, l - 8 - highlight[1], f);
+        } else
+                fwrite((const char*) data + 8, 1, l - 8, f);
         fputc('\n', f);
 
         return 0;
@@ -986,7 +1040,8 @@ static int (*output_funcs[_OUTPUT_MODE_MAX])(
                 OutputMode mode,
                 unsigned n_columns,
                 OutputFlags flags,
-                Set *output_fields) = {
+                Set *output_fields,
+                size_t highlight[2]) = {
 
         [OUTPUT_SHORT] = output_short,
         [OUTPUT_SHORT_ISO] = output_short,
@@ -1010,6 +1065,7 @@ int output_journal(
                 unsigned n_columns,
                 OutputFlags flags,
                 char **output_fields,
+                size_t highlight[2],
                 bool *ellipsized) {
 
         int ret;
@@ -1030,7 +1086,7 @@ int output_journal(
                         return ret;
         }
 
-        ret = output_funcs[mode](f, j, mode, n_columns, flags, fields);
+        ret = output_funcs[mode](f, j, mode, n_columns, flags, fields, highlight);
 
         if (ellipsized && ret > 0)
                 *ellipsized = true;
@@ -1112,7 +1168,7 @@ static int show_journal(FILE *f,
                         line++;
                         maybe_print_begin_newline(f, &flags);
 
-                        r = output_journal(f, j, mode, n_columns, flags, NULL, ellipsized);
+                        r = output_journal(f, j, mode, n_columns, flags, NULL, NULL, ellipsized);
                         if (r < 0)
                                 return r;
                 }