X-Git-Url: https://git.distorted.org.uk/~mdw/mLib/blobdiff_plain/8128dcdfa57d0a792c4e221aae5b4886eaef72d0..d056fbdff1c5a26be055c38eee4c273ee6a0cba7:/sys/mdup.3

diff --git a/sys/mdup.3 b/sys/mdup.3
index 9ce3b85..567da6a 100644
--- a/sys/mdup.3
+++ b/sys/mdup.3
@@ -17,15 +17,31 @@
 \h'-\w'\\$1\ 'u'\\$1\ \c
 .ft P
 ..
-.ie t .ds o \(bu
-.el .ds o o
+.ie t \{\
+.  ds o \(bu
+.  de VP
+.    sp .4v
+..
+\}
+.el \{\
+.  ds o o
+.  de VP
+.    sp
+..
+\}
 .TH mdup 3 "4 January" "Straylight/Edgeware" "mLib utilities library"
 .SH NAME
 mdup \- renumber file descriptors
 .SH SYNOPSIS
 .nf
 .B "#include <mLib/mdup.h>"
-
+.PP
+.ta 2n
+.B "typedef struct {"
+.B "	int cur;"
+.B "	int want;"
+.B "} mdup_fd;"
+.PP
 .BI "int mdup(mdup_fd *" v ", size_t " n ");"
 .fi
 .SH DESCRIPTION
@@ -41,16 +57,7 @@ to a vector of
 .B mdup_fd
 structures, and the length
 .I n
-of this vector, in elements.  The
-.B mdup_fd
-structure is defined as
-.VS
-typedef struct mdup_fd {
-  int cur;
-  int want;
-} mdup_fd;
-.VE
-Each `slot' (element) in the vector
+of this vector, in elements.  Each `slot' (element) in the vector
 .I v
 represents a file.  The slot's
 .B cur
@@ -116,17 +123,18 @@ this.
 int p_in[2] = P_INIT, p_out[2] = P_INIT, p_err[2] = P_INIT;
 pid_t kid = -1;
 int i;
-
+.VP
 if (pipe(p_in) || pipe(p_out) || pipe(p_err)) goto error;
 if ((kid = fork()) < 0) goto error;
 if (!kid) {
-  if (dup2(p_in[0], STDIN_FILENO) < 0 ||
-      dup2(p_out[1], STDOUT_FILENO) < 0 ||
-      dup2(p_err[2], STDERR_FILENO) < 0 ||
-      close(p_in[0]) || close(p_out[0]) || close(p_err[0]) ||
-      close(p_in[1]) || close(p_out[1]) || close(p_err[1]))
-    _exit(127);
-  execvp("/bin/sh", "sh", "-c", "...", (char *)0);
+.ta 2n 4n 2n+\w'\fBif ('u
+	if (dup2(p_in[0], STDIN_FILENO) < 0 ||
+			dup2(p_out[1], STDOUT_FILENO) < 0 ||
+			dup2(p_err[2], STDERR_FILENO) < 0 ||
+			close(p_in[0]) || close(p_out[0]) || close(p_err[0]) ||
+			close(p_in[1]) || close(p_out[1]) || close(p_err[1]))
+		_exit(127);
+	execvp("/bin/sh", "sh", "-c", "...", (char *)0);
 }
 \&...
 .VE
@@ -149,22 +157,23 @@ the child.
 Here's how to rewrite the above function using
 .BR mdup .
 .VS
+.ta 2n 4n 2n+\w'\fBmd[0].cur = p_out[1]; 'u
 #define P_INIT { \-1, \-1 }
 int p_in[2] = P_INIT, p_out[2] = P_INIT, p_err[2] = P_INIT;
 pid_t kid = -1;
 mdup_fd md[3];
 int i;
-
+.VP
 if (pipe(p_in) || pipe(p_out) || pipe(p_err)) goto error;
 if ((kid = fork()) < 0) goto error;
 if (!kid) {
-  if (close(p_in[1] || close(p_out[0]) || close(p_err[0]))
-    goto _exit(127);
-  md[0].cur = p_in[0];  md[0].want = STDIN_FILENO;
-  md[1].cur = p_out[1]; md[1].want = STDOUT_FILENO;
-  md[2].cur = p_err[1]; md[2].want = STDERR_FILENO;
-  if (mdup(md, 3)) _exit(127);
-  execvp("/bin/sh", "sh", "-c", "...", (char *)0);
+	if (close(p_in[1] || close(p_out[0]) || close(p_err[0]))
+		goto _exit(127);
+	md[0].cur = p_in[0];		md[0].want = STDIN_FILENO;
+	md[1].cur = p_out[1];		md[1].want = STDOUT_FILENO;
+	md[2].cur = p_err[1];		md[2].want = STDERR_FILENO;
+	if (mdup(md, 3)) _exit(127);
+	execvp("/bin/sh", "sh", "-c", "...", (char *)0);
 }
 \&...
 .VE
@@ -185,4 +194,3 @@ wanted ends of the pipes.
 .BR mLib (3).
 .SH AUTHOR
 Mark Wooding, <mdw@distorted.org.uk>
-