Implement man.

To look up docs on my netbook and server. Practically deroff.1, with
heuristic for where to put spaces and newlines. How would you simplify
file resolution and bzcat? What have I got wrong when escaping slashes,
because while \-\^\- is -- ok, \-\- becomes -\-, e.g. in git-pull.1?

1 files changed, 112 insertions, 0 deletions

diff --git a/toys/pending/man.c b/toys/pending/man.c
new file mode 100644
index 00000000..57f77c61
--- /dev/null
+++ b/toys/pending/man.c
@@ -0,0 +1,112 @@
+/* man.c - Read system documentation
+ *
+ * Copyright 2019 makepost <makepost@firemail.cc>
+ *
+ * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/man.html
+
+USE_MAN(NEWTOY(man, "<1>1", TOYFLAG_USR|TOYFLAG_BIN))
+
+config MAN
+  bool "man"
+  default n
+  help
+    usage: man COMMAND
+
+    Read manual for system command.
+*/
+
+#define FOR_man
+#include <toys.h>
+#include <glob.h>
+
+GLOBALS(
+  char any, cell, *f, *line;
+)
+
+static void newln()
+{
+  if (TT.any) putchar('\n');
+  if (TT.any && TT.cell != 2) putchar('\n'); // gawk alias
+  TT.any = TT.cell = 0;
+}
+static void put(char *x) { while (*x && *x != '\n') TT.any = putchar(*x++); }
+
+static void s(char *x, char *y) { // Substitute with same length or shorter.
+  int i = strlen(x), j = strlen(y), k, l;
+  for (k = 0; TT.line[k]; k++) if (!strncmp(x, &TT.line[k], i)) {
+    memmove(&TT.line[k], y, j);
+    for (l = k += j; TT.line[l]; l++) TT.line[l] = TT.line[l + i - j];
+  }
+}
+
+static char start(char *x) { return !strncmp(x, TT.line, strlen(x)); }
+static void trim(char *x) { if (start(x)) while (*x++) TT.line++; }
+
+static void do_man(FILE *fp)
+{
+  size_t len = 0;
+  char *line = 0;
+  while (getline(&line, &len, fp) > 0) {
+    TT.line = line;
+    s("\\fB", ""), s("\\fI", ""), s("\\fP", ""), s("\\fR", ""); // bash bold,ita
+    s("\\(aq", "'"), s("\\(cq", "'"), s("\\(dq", "\""); // bash,rsync quote
+    s("\\*(lq", "\""), s("\\*(rq", "\""); // gawk quote
+    s("\\(bu", "*"), s("\\(bv", "|"); // bash symbol
+    s("\\&", ""), s("\\f(CW", ""); // gawk,rsync fancy
+    s("\\-", "-"), s("\\(", ""), s("\\^", ""), s("\\e", "\\"); // bash escape
+    s("\\*(", "#"); // gawk var
+    if (start(".BR")) trim(".BR "), s(" ", ""); // bash boldpunct
+    if (start(".IP")) newln(), trim(".IP "); // bash list
+    if (start(".IR")) trim(".IR "), s(" ", ""); // bash itapunct
+    trim(".B "); // bash bold
+    trim(".BI "); // gawk boldita
+    trim(".FN "); // bash filename
+    trim(".I "); // bash ita
+    trim(".if n "); // bash nroff
+    if (start(".PP")) newln(); // bash paragraph
+    else if (start(".SM")); // bash small
+    else if (start(".S")) newln(), put(TT.line + 4), newln(); // bash section
+    else if (start(".so")) put("See "), put(basename(TT.line + 4)); // lastb
+    else if (start(".TH")) s("\"", " "), put(TT.line + 4); // gawk,git head
+    else if (start(".TP")) newln(), TT.cell = 1; // bash table
+    else if (start(".") || start("\'")); // bash,git garbage
+    else if (!*TT.line); // emerge
+    else ((TT.cell != 0) && TT.cell++), put(" "), put(TT.line);
+  }
+  newln();
+  free(line);
+  fclose(fp);
+}
+
+static FILE *bzcat()
+{
+  char cmd[FILENAME_MAX];
+  snprintf(cmd, sizeof(cmd), "bzcat %s", TT.f);
+  return popen(cmd, "r");
+}
+
+static char *find(char *path, int suf)
+{
+  glob_t g;
+  int i;
+  size_t len = strlen(*toys.optargs);
+  char *name;
+  glob(path, 0, 0, &g);
+  for (i = 0; !TT.f && i < g.gl_pathc; i++) {
+    name = basename(g.gl_pathv[i]);
+    if (strlen(name) == len + suf && !strncmp(name, *toys.optargs, len))
+      TT.f = strdup(g.gl_pathv[i]);
+  }
+  globfree(&g);
+  return TT.f;
+}
+
+void man_main(void)
+{
+  chdir("/usr/share/man");
+  if (find("man?/*.?.bz2", 6)) do_man(bzcat()); // curl_strequal
+  else if (find("man?/*.bz2", 4)) do_man(bzcat()); // curl_strequal.3
+  else if (find("man?/*.?", 2)) do_man(fopen(TT.f, "r")); // curl_strnequal
+  else if (find("man?/*", 0)) do_man(fopen(TT.f, "r")); // curl_strnequal.3
+  if (TT.f) free(TT.f);
+}