3 files changed, 41 insertions, 17 deletions

diff --git a/editors/awk.c b/editors/awk.c
index 509f4ddd8..4799091ec 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -405,7 +405,7 @@ static const char tokenlist[] ALIGN1 =
 
 #define OC_B  OC_BUILTIN
 
-static const uint32_t tokeninfo[] = {
+static const uint32_t tokeninfo[] ALIGN4 = {
         0,
         0,
         OC_REGEXP,
@@ -1767,12 +1767,34 @@ static void fsrealloc(int size)
         nfields = size;
 }
 
+static int regexec1_nonempty(const regex_t *preg, const char *s, regmatch_t pmatch[])
+{
+        int r = regexec(preg, s, 1, pmatch, 0);
+        if (r == 0 && pmatch[0].rm_eo == 0) {
+                /* For example, happens when FS can match
+                 * an empty string (awk -F ' *'). Logically,
+                 * this should split into one-char fields.
+                 * However, gawk 5.0.1 searches for first
+                 * _non-empty_ separator string match:
+                 */
+                size_t ofs = 0;
+                do {
+                        ofs++;
+                        if (!s[ofs])
+                                return REG_NOMATCH;
+                        regexec(preg, s + ofs, 1, pmatch, 0);
+                } while (pmatch[0].rm_eo == 0);
+                pmatch[0].rm_so += ofs;
+                pmatch[0].rm_eo += ofs;
+        }
+        return r;
+}
+
 static int awk_split(const char *s, node *spl, char **slist)
 {
-        int l, n;
+        int n;
         char c[4];
         char *s1;
-        regmatch_t pmatch[2]; // TODO: why [2]? [1] is enough...
 
         /* in worst case, each char would be a separate field */
         *slist = s1 = xzalloc(strlen(s) * 2 + 3);
@@ -1789,29 +1811,31 @@ static int awk_split(const char *s, node *spl, char **slist)
                         return n; /* "": zero fields */
                 n++; /* at least one field will be there */
                 do {
+                        int l;
+                        regmatch_t pmatch[2]; // TODO: why [2]? [1] is enough...
+
                         l = strcspn(s, c+2); /* len till next NUL or \n */
-                        if (regexec(icase ? spl->r.ire : spl->l.re, s, 1, pmatch, 0) == 0
+                        if (regexec1_nonempty(icase ? spl->r.ire : spl->l.re, s, pmatch) == 0
                          && pmatch[0].rm_so <= l
                         ) {
+                                /* if (pmatch[0].rm_eo == 0) ... - impossible */
                                 l = pmatch[0].rm_so;
-                                if (pmatch[0].rm_eo == 0) {
-                                        l++;
-                                        pmatch[0].rm_eo++;
-                                }
                                 n++; /* we saw yet another delimiter */
                         } else {
                                 pmatch[0].rm_eo = l;
                                 if (s[l])
                                         pmatch[0].rm_eo++;
                         }
-                        memcpy(s1, s, l);
-                        /* make sure we remove *all* of the separator chars */
-                        do {
-                                s1[l] = '\0';
-                        } while (++l < pmatch[0].rm_eo);
-                        nextword(&s1);
+                        s1 = mempcpy(s1, s, l);
+                        *s1++ = '\0';
                         s += pmatch[0].rm_eo;
                 } while (*s);
+
+                /* echo a-- | awk -F-- '{ print NF, length($NF), $NF }'
+                 * should print "2 0 ":
+                 */
+                *s1 = '\0';
+
                 return n;
         }
         if (c[0] == '\0') {  /* null split */
@@ -2030,7 +2054,7 @@ static ssize_t FAST_FUNC safe_read_strip_cr(int fd, void *buf, size_t count)
 static int awk_getline(rstream *rsm, var *v)
 {
         char *b;
-        regmatch_t pmatch[2];
+        regmatch_t pmatch[2]; // TODO: why [2]? [1] is enough...
         int size, a, p, pp = 0;
         int fd, so, eo, r, rp;
         char c, *m, *s;
diff --git a/editors/patch.c b/editors/patch.c
index aaa253591..110176630 100644
--- a/editors/patch.c
+++ b/editors/patch.c
@@ -31,7 +31,7 @@
 //kbuild:lib-$(CONFIG_PATCH) += patch.o
 
 //usage:#define patch_trivial_usage
-//usage:       "[OPTIONS] [ORIGFILE [PATCHFILE]]"
+//usage:       "[-RNE] [-p N] [-i DIFF] [ORIGFILE [PATCHFILE]]"
 //usage:#define patch_full_usage "\n\n"
 //usage:       "        -p N    Strip N leading components from file names"
 //usage:     "\n        -i DIFF Read DIFF instead of stdin"
diff --git a/editors/vi.c b/editors/vi.c
index 131c018a2..bfe05d613 100644
--- a/editors/vi.c
+++ b/editors/vi.c
@@ -166,7 +166,7 @@
 //kbuild:lib-$(CONFIG_VI) += vi.o
 
 //usage:#define vi_trivial_usage
-//usage:       "[OPTIONS] [FILE]..."
+//usage:       IF_FEATURE_VI_COLON("[-c CMD] ")IF_FEATURE_VI_READONLY("[-R] ")"[FILE]..."
 //usage:#define vi_full_usage "\n\n"
 //usage:       "Edit FILE\n"
 //usage:        IF_FEATURE_VI_COLON(