libexplain
1.4.D001
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00001 /* 00002 * libexplain - Explain errno values returned by libc functions 00003 * Copyright (C) 2008, 2009, 2013 Peter Miller 00004 * 00005 * This program is free software; you can redistribute it and/or modify it 00006 * under the terms of the GNU Lesser General Public License as published by 00007 * the Free Software Foundation; either version 3 of the License, or (at 00008 * your option) any later version. 00009 * 00010 * This program is distributed in the hope that it will be useful, 00011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00013 * Lesser General Public License for more details. 00014 * 00015 * You should have received a copy of the GNU Lesser General Public License 00016 * along with this program. If not, see <http://www.gnu.org/licenses/>. 00017 */ 00018 00019 #include <libexplain/ac/errno.h> 00020 00021 #include <libexplain/buffer/enomem.h> 00022 #include <libexplain/buffer/errno/fork.h> 00023 #include <libexplain/buffer/errno/generic.h> 00024 #include <libexplain/buffer/gettext.h> 00025 #include <libexplain/explanation.h> 00026 #include <libexplain/option.h> 00027 00028 00029 static void 00030 explain_buffer_errno_fork_system_call(explain_string_buffer_t *sb, 00031 int errnum) 00032 { 00033 (void)errnum; 00034 explain_string_buffer_puts(sb, "fork()"); 00035 } 00036 00037 00038 void 00039 explain_buffer_errno_fork_explanation(explain_string_buffer_t *sb, 00040 int errnum, const char *syscall_name) 00041 { 00042 /* 00043 * http://www.opengroup.org/onlinepubs/009695399/functions/fork.html 00044 */ 00045 switch (errnum) 00046 { 00047 case EAGAIN: 00048 explain_buffer_gettext 00049 ( 00050 sb, 00051 /* 00052 * xgettext: This message is used to explain fork(2) errors, 00053 * when no more specific cause can be determined. 00054 */ 00055 i18n("the system lacked the necessary resources to create " 00056 "another process; or, the system-imposed limit on the total " 00057 "number of processes under execution system-wide would be " 00058 "exceeded; or, the system-imposed limit on the total number " 00059 "of processes under execution by a single user {CHILD_MAX} " 00060 "would be exceeded") 00061 ); 00062 00063 /* 00064 * FIXME: distinguish the 4 cases 00065 * 00066 * sysconf(_SC_CHILD_MAX) 00067 * The max number of simultaneous processes per user ID. Must 00068 * not be less than _POSIX_CHILD_MAX (25). 00069 * 00070 * getrlimit(RLIMIT_NPROC) 00071 * The maximum number of processes (or, more precisely on 00072 * Linux, threads) that can be created for the real user ID of 00073 * the calling process. Upon encountering this limit, fork(2) 00074 * fails with the error EAGAIN. 00075 */ 00076 #ifdef HAVE_SYS_CAPABILITY_H 00077 if (explain_option_dialect_specific()) 00078 { 00079 explain_string_buffer_puts(sb, ", "); 00080 explain_buffer_gettext 00081 ( 00082 sb, 00083 /* 00084 * xgettext: This message is used when explaining 00085 * the capabilities required to exceed system limits 00086 * on the number of processes a user may execute 00087 * simultaniously. 00088 */ 00089 i18n("to exceed the limit on the number of processes, " 00090 "the process must have either the CAP_SYS_ADMIN or the " 00091 "CAP_SYS_RESOURCE capability") 00092 ); 00093 } 00094 #endif 00095 break; 00096 00097 case ENOMEM: 00098 /* 00099 * The Open Group Base Specifications Issue 6 00100 * IEEE Std 1003.1, 2004 Edition 00101 * 00102 * fork() Rationale states 00103 * "The [ENOMEM] error value is reserved for those 00104 * implementations that detect and distinguish such a 00105 * condition. This condition occurs when an implementation 00106 * detects that there is not enough memory to create the 00107 * process. This is intended to be returned when [EAGAIN] is 00108 * inappropriate because there can never be enough memory 00109 * (either primary or secondary storage) to perform the 00110 * operation. Since fork() duplicates an existing process, 00111 * this must be a condition where there is sufficient memory 00112 * for one such process, but not for two. Many historical 00113 * implementations actually return [ENOMEM] due to temporary 00114 * lack of memory, a case that is not generally distinct from 00115 * [EAGAIN] from the perspective of a conforming application. 00116 * 00117 * "Part of the reason for including the optional error 00118 * [ENOMEM] is because the SVID specifies it and it should 00119 * be reserved for the error condition specified there. The 00120 * condition is not applicable on many implementations." 00121 */ 00122 explain_buffer_enomem_kernel(sb); 00123 break; 00124 00125 default: 00126 explain_buffer_errno_generic(sb, errnum, syscall_name); 00127 break; 00128 } 00129 } 00130 00131 00132 void 00133 explain_buffer_errno_fork(explain_string_buffer_t *sb, int errnum) 00134 { 00135 explain_explanation_t exp; 00136 00137 explain_explanation_init(&exp, errnum); 00138 explain_buffer_errno_fork_system_call(&exp.system_call_sb, errnum); 00139 explain_buffer_errno_fork_explanation(&exp.explanation_sb, errnum, "fork"); 00140 explain_explanation_assemble(&exp, sb); 00141 } 00142 00143 00144 /* vim: set ts=8 sw=4 et : */