From a263b49422590feb52789266f3e9bc89cb746b96 Mon Sep 17 00:00:00 2001
From: "Steffen (Daode) Nurpmeso" <steffen@sdaoden.eu>
Date: Tue, 19 Apr 2016 14:20:28 +0200
Subject: [PATCH] Add n_strescsep() (allows backslash escaped separator)..

P.S.: during development of v14.9 it has become clear that we will
start being backward-incompatible, and support for sh(1)ell-style
argument quoting has been implemented on the [topic/wysh] branch.
There we've also added n_shell_sep(), which is the true successor
of strsep(), as it'll allow the user to specify _exactly_ what she
wants, and in a known and standardized syntax.  Of course much has
to change in the future to get there, but nonetheless: adding such
a fragile and non-standard (but for RFC 1524) syntax, like
n_strescsep(), is thus only a temporary solution.

Therefore usage of this function will be removed again as far as
possible during v14.9 development, and once only *customhdr*
remains (which is itself temporary), we'll make this function
local, to be removed in v15.
---
 attachments.c |  2 +-
 nail.1        | 10 ++++++----
 nailfuns.h    |  6 +++++-
 nam_a_grp.c   |  2 +-
 strings.c     | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/attachments.c b/attachments.c
index 127a0f4e..41b4d6db 100644
--- a/attachments.c
+++ b/attachments.c
@@ -385,7 +385,7 @@ append_attachments(struct attachment **aphead, char *names)
    struct attachment *xaph, *nap;
    NYD_ENTER;
 
-   while ((cp = n_strsep(&names, ',', 1)) != NULL) {
+   while ((cp = n_strescsep(&names, ',', TRU1)) != NULL) {
       xaph = add_attachment(*aphead, fexpand_nshell_quote(cp), &nap);
       if (xaph != NULL) {
          *aphead = xaph;
diff --git a/nail.1 b/nail.1
index 7d675b2d..a3895e24 100644
--- a/nail.1
+++ b/nail.1
@@ -4690,8 +4690,9 @@ arguments are specified for the
 .Ic \&\&~@
 command they are treated as a comma-separated list of files,
 which are all expanded and appended to the end of the attachment list.
-(Filenames with commas, or with leading or trailing whitespace can only
-be added via the command line or the first method.
+(Commas need to be escaped with backslash, but filenames with leading or
+trailing whitespace can only be added via the command line or the first
+method.
 Message attachments can only be added via the first method;
 filenames which clash with message numbers can only be added via the
 command line or the second method.)
@@ -5454,9 +5455,10 @@ and
 \*(OB A variable counterpart of the
 .Ic customhdr
 command (see there for documentation), interpreted as a comma-separated
-list of custom headers to be injected, e.g.:
+list of custom headers to be injected, to include commas in the header
+bodies escape them with backslash, e.g.:
 .Pp
-.Dl set customhdr="Hdr1: Body1, Hdr2: Body2"
+.Dl set customhdr="Hdr1: Body1-1\e, Body1-2,  Hdr2: Body2"
 .
 .Mx
 .It Va datefield
diff --git a/nailfuns.h b/nailfuns.h
index 1cdad0f3..49269ec4 100644
--- a/nailfuns.h
+++ b/nailfuns.h
@@ -1867,8 +1867,12 @@ FL int         anyof(char const *s1, char const *s2);
 /* Treat *iolist as a sep separated list of strings; find and return the
  * next entry, trimming surrounding whitespace, and point *iolist to the next
  * entry or to NULL if no more entries are contained.  If ignore_empty is not
- * set empty entries are started over.  Return NULL or an entry */
+ * set empty entries are started over.
+ * strescsep will assert that sep is not NULL, and allows escaping of the
+ * separator character with a backslash.
+ * Return NULL or an entry */
 FL char *      n_strsep(char **iolist, char sep, bool_t ignore_empty);
+FL char *      n_strescsep(char **iolist, char sep, bool_t ignore_empty);
 
 /* Copy a string, lowercasing it as we go; *size* is buffer size of *dest*;
  * *dest* will always be terminated unless *size* is 0 */
diff --git a/nam_a_grp.c b/nam_a_grp.c
index 92086fa5..6ff8b8d3 100644
--- a/nam_a_grp.c
+++ b/nam_a_grp.c
@@ -1823,7 +1823,7 @@ n_customhdr_query(void){ /* XXX Uses salloc()! */
       if(vp != NULL){
          char *buf = savestr(vp);
 jch_outer:
-         while((vp = n_strsep(&buf, ',', TRU1)) != NULL){
+         while((vp = n_strescsep(&buf, ',', TRU1)) != NULL){
             ui32_t nl, bl;
             char const *nstart, *cp;
 
diff --git a/strings.c b/strings.c
index f1dff729..7ad15fc6 100644
--- a/strings.c
+++ b/strings.c
@@ -651,6 +651,58 @@ n_strsep(char **iolist, char sep, bool_t ignore_empty)
    return base;
 }
 
+FL char *
+n_strescsep(char **iolist, char sep, bool_t ignore_empty){
+   char *cp, c, *base;
+   bool_t isesc, anyesc;
+   NYD2_ENTER;
+
+   assert(sep != '\0');
+
+   for(base = *iolist; base != NULL; base = *iolist){
+      while((c = *base) != '\0' && blankspacechar(c))
+         ++base;
+
+      for(isesc = anyesc = FAL0, cp = base;; ++cp){
+         if(UNLIKELY((c = *cp) == '\0')){
+            *iolist = NULL;
+            break;
+         }else if(!isesc){
+            if(c == sep){
+               *iolist = cp + 1;
+               break;
+            }
+            isesc = (c == '\\');
+         }else{
+            isesc = FAL0;
+            anyesc |= (c == sep);
+         }
+      }
+
+      while(cp > base && blankspacechar(cp[-1]))
+         --cp;
+      *cp = '\0';
+
+      if(*base != '\0'){
+         if(anyesc){
+            char *ins;
+
+            for(ins = cp = base;; ++ins)
+               if((c = *cp) == '\\' && cp[1] == sep){
+                  *ins = sep;
+                  cp += 2;
+               }else if((*ins = (++cp, c)) == '\0')
+                  break;
+         }
+         break;
+      }
+      if(!ignore_empty)
+         break;
+   }
+   NYD2_LEAVE;
+   return base;
+}
+
 FL void
 i_strcpy(char *dest, char const *src, size_t size)
 {
-- 
2.11.4.GIT