[PATCH v2 1/2] system_data_types.7: Add 'error_t'

[Alejandro Colomar <colomar.6.4.3@gmail.com>]

Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
---
 man7/system_data_types.7 | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/man7/system_data_types.7 b/man7/system_data_types.7
index 49ca2d8e1..4930aac8b 100644
--- a/man7/system_data_types.7
+++ b/man7/system_data_types.7
@@ -199,6 +199,45 @@ See also the
 .I float_t
 type in this page.
 .RE
+.\"------------------------------------- error_t ----------------------/
+.TP
+.I error_t
+.RS
+Include:
+.IR <argz.h> ,
+or
+.IR <envz.h> .
+Alternatively,
+.IR <errno.h> .
+.PP
+An integer type
+used for error reporting.
+A value of 0 means success, and nonzero means failure.
+Portable programs should use
+.I int
+instead.
+.PP
+Conforming to:
+Present in glibc.
+It is not standardized by the C language standard nor POSIX.
+.PP
+Notes:
+C11 standardized a similar type as an optional extension:
+.IR errno_t .
+However,
+.I errno_t
+is not present in POSIX.
+.PP
+.I <errno.h>
+defines this type if the macro
+.B _GNU_SOURCE
+is defined before including the header.
+.PP
+See also:
+.BR argz_add (3),
+.BR envz_add (3),
+.BR feature_test_macros (7)
+.RE
 .\"------------------------------------- fd_set -----------------------/
 .TP
 .I fd_set
-- 
2.28.0