1 files changed, 36 insertions, 16 deletions

diff --git a/editors/awk.c b/editors/awk.c
index 75f757dbb..17710e57e 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -2357,36 +2357,55 @@ static char *awk_printf(node *n, size_t *len)
 
         b = NULL;
         i = 0;
-        while (*f) { /* "print one format spec" loop */
+        while (1) { /* "print one format spec" loop */
                 char *s;
                 char c;
                 char sv;
                 var *arg;
                 size_t slen;
 
+                /* Find end of the next format spec, or end of line */
                 s = f;
-                while (*f && (*f != '%' || *++f == '%'))
-                        f++;
-                while (*f && !isalpha(*f)) {
-                        if (*f == '*')
-                                syntax_error("%*x formats are not supported");
+                while (1) {
+                        c = *f;
+                        if (!c) /* no percent chars found at all */
+                                goto nul;
                         f++;
+                        if (c == '%')
+                                break;
                 }
+                /* we are past % in "....%..." */
                 c = *f;
-                if (!c) {
-                        /* Tail of fmt with no percent chars,
-                         * or "....%" (percent seen, but no format specifier char found)
-                         */
-                        slen = strlen(s);
-                        goto tail;
+                if (!c) /* "....%" */
+                        goto nul;
+                if (c == '%') { /* "....%%...." */
+                        slen = f - s;
+                        s = xstrndup(s, slen);
+                        f++;
+                        goto append; /* print "....%" part verbatim */
                 }
-                sv = *++f;
-                *f = '\0';
+                while (1) {
+                        if (isalpha(c))
+                                break;
+                        if (c == '*')
+                                syntax_error("%*x formats are not supported");
+                        c = *++f;
+                        if (!c) { /* "....%...." and no letter found after % */
+                                /* Example: awk 'BEGIN { printf "^^^%^^^\n"; }' */
+ nul:
+                                slen = f - s;
+                                goto tail; /* print remaining string, exit loop */
+                        }
+                }
+                /* we are at A in "....%...A..." */
+
                 arg = evaluate(nextarg(&n), TMPVAR);
 
                 /* Result can be arbitrarily long. Example:
                  *  printf "%99999s", "BOOM"
                  */
+                sv = *++f;
+                *f = '\0';
                 if (c == 'c') {
                         char cc = is_numeric(arg) ? getvar_i(arg) : *getvar_s(arg);
                         char *r = xasprintf(s, cc ? cc : '^' /* else strlen will be wrong */);
@@ -2405,13 +2424,14 @@ static char *awk_printf(node *n, size_t *len)
                                 } else if (strchr("eEfFgGaA", c)) {
                                         s = xasprintf(s, d);
                                 } else {
+//TODO: GNU Awk 5.0.1: printf "%W" prints "%W", does not error out
                                         syntax_error(EMSG_INV_FMT);
                                 }
                         }
                         slen = strlen(s);
                 }
                 *f = sv;
-
+ append:
                 if (i == 0) {
                         b = s;
                         i = slen;
@@ -2421,7 +2441,7 @@ static char *awk_printf(node *n, size_t *len)
                 b = xrealloc(b, i + slen + 1);
                 strcpy(b + i, s);
                 i += slen;
-                if (!c) /* tail? */
+                if (!c) /* s is NOT allocated and this is the last part of string? */
                         break;
                 free(s);
         }