options: allow using [ ] for quoting in sub-options

This is an attempt to make quoting of sub-option values less awkward,
even if it works only with some shells. This is needed mainly for
vf_lavfi. Also update the vf_lavfi manpage section.

2 files changed, 21 insertions, 7 deletions

diff --git a/DOCS/man/en/vf.rst b/DOCS/man/en/vf.rst
index e534c73ec3..846d3ffac6 100644
--- a/DOCS/man/en/vf.rst
+++ b/DOCS/man/en/vf.rst
@@ -383,14 +383,21 @@ lavfi=graph[:sws_flags]
 
         *EXAMPLE*:
 
-        ``'--vf=lavfi="gradfun=20:30"'``
-            gradfun filter with non-sensical parameters. The ``'`` quotes are
-            for the shell. Otherwise, the shell would remove the ``"`` quotes.
+        ``-vf lavfi=[gradfun=20:30,vflip]``
+            gradfun filter with nonsense parameters, followed by a vflip
+            filter. (This demonstrates how libavfilter takes a graph and not
+            just a single filter.) The filter graph string is quoted with
+            ``[`` and ``]``. This requires no additional quoting or escaping
+            with some shells (like bash), while others (like zsh) require
+            additional ``"`` quotes around the option string.
+
+        ``'--vf=lavfi="gradfun=20:30,vflip"'``
+            same as before, but uses quoting that should be safe with all
+            shells. The outer ``'`` quotes make sure that the shell doesn't
+            remove the ``"`` quotes needed by mpv.
 
         ``'--vf=lavfi=graph="gradfun=radius=30:strength=20,vflip"'``
-            same as before, but uses named parameters. Also a vflip filter is
-            appended, demonstrating how libavfilter actually takes a graph
-            description and not a single filter.
+            same as before, but uses named parameters for everything.
 
     <sws_flags>
         If libavfilter inserts filters for pixel format conversion, this
diff --git a/core/m_option.c b/core/m_option.c
index a0b4808e2e..a667471407 100644
--- a/core/m_option.c
+++ b/core/m_option.c
@@ -1167,6 +1167,13 @@ static int read_subparam(bstr optname, bstr *str, bstr *out_subparam)
             return M_OPT_INVALID;
         }
         p = bstr_cut(p, 1);
+    } else if (bstr_eatstart0(&p, "[")) {
+        if (!bstr_split_tok(p, "]", &subparam, &p)) {
+            mp_msg(MSGT_CFGPARSER, MSGL_ERR,
+                   "Terminating ']' missing for '%.*s'\n",
+                   BSTR_P(optname));
+            return M_OPT_INVALID;
+        }
     } else if (bstr_eatstart0(&p, "%")) {
         int optlen = bstrtoll(p, &p, 0);
         if (!bstr_startswith0(p, "%") || (optlen > p.len - 1)) {
@@ -1180,7 +1187,7 @@ static int read_subparam(bstr optname, bstr *str, bstr *out_subparam)
     } else {
         // Skip until the next character that could possibly be a meta
         // character in option parsing.
-        int optlen = bstrcspn(p, ":=,\\%\"'");
+        int optlen = bstrcspn(p, ":=,\\%\"'[]");
         subparam = bstr_splice(p, 0, optlen);
         p = bstr_cut(p, optlen);
     }