15368824317

Committed 31 May 2025 06:14PM UTC coverage: 72.029% (+0.005%) from 72.024%

Build # 15368824317

Build Type

push

github

Committed by

yuwata

Commit Message

mount-util: avoid unnecessary mount_setattr() call in make_fsmount()

If .attr_set is zero (and .att_clr, .propagation too), then there's no
point in calling mount_setattr().

Fixes: #37062

Note that this optimization is not precisely load-bearing anymore, since
3cc23a2c2 got merged which removes the
only caller of make_fsmount() that might trigger it. But it's worth
fixing generic code anyway, in case it gets used like this later again.

Coverage Stats

3 of 3 new or added lines in 1 file covered. (100.0%)

891 existing lines in 47 files now uncovered.

299583 of 415921 relevant lines covered (72.03%)

703729.28 hits per line

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81.82

/src/basic/errno-util.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once

#include <string.h>

#include "forward.h"

/* strerror(3) says that glibc uses a maximum length of 1024 bytes. */
#define ERRNO_BUF_LEN           1024

/* Note: the lifetime of the compound literal is the immediately surrounding block,
 * see C11 §6.5.2.5, and
 * https://stackoverflow.com/questions/34880638/compound-literal-lifetime-and-if-blocks
 *
 * Note that we use the GNU variant of strerror_r() here. */
#define STRERROR(errnum) strerror_r(ABS(errnum), (char[ERRNO_BUF_LEN]){}, ERRNO_BUF_LEN)

/* A helper to print an error message or message for functions that return 0 on EOF.
 * Note that we can't use ({ … }) to define a temporary variable, so errnum is
 * evaluated twice. */
#define STRERROR_OR_EOF(errnum) ((errnum) != 0 ? STRERROR(errnum) : "Unexpected EOF")

static inline void _reset_errno_(int *saved_errno) {
        if (*saved_errno < 0) /* Invalidated by UNPROTECT_ERRNO? */
                return;

        errno = *saved_errno;
}

#define PROTECT_ERRNO                           \
        _cleanup_(_reset_errno_) _unused_ int _saved_errno_ = errno

#define UNPROTECT_ERRNO                         \
        do {                                    \
                errno = _saved_errno_;          \
                _saved_errno_ = -1;             \
        } while (false)

#define LOCAL_ERRNO(value)                      \
        PROTECT_ERRNO;                          \
        errno = ABS(value)

#define return_with_errno(r, err)                     \
        do {                                          \
                errno = ABS(err);                     \
                return r;                             \
        } while (false)

static inline int negative_errno(void) {
        /* This helper should be used to shut up gcc if you know 'errno' is
         * negative. Instead of "return -errno;", use "return negative_errno();"
         * It will suppress bogus gcc warnings in case it assumes 'errno' might
         * be 0 and thus the caller's error-handling might not be triggered. */
        assert_return(errno > 0, -EINVAL);
        return -errno;
}

static inline int RET_NERRNO(int ret) {

        /* Helper to wrap system calls in to make them return negative errno errors. This brings system call
         * error handling in sync with how we usually handle errors in our own code, i.e. with immediate
         * returning of negative errno. Usage is like this:
         *
         *     …
         *     r = RET_NERRNO(unlink(t));
         *     …
         *
         * or
         *
         *     …
         *     fd = RET_NERRNO(open("/etc/fstab", O_RDONLY|O_CLOEXEC));
         *     …
         */

        if (ret < 0)
                return negative_errno();

        return ret;
}

/* Collect possible errors in <acc>, so that the first error can be returned.
 * Returns (possibly updated) <acc>. */
#define RET_GATHER(acc, err)                    \
        ({                                      \
                int *__a = &(acc), __e = (err); \
                if (*__a >= 0 && __e < 0)       \
                        *__a = __e;             \
                *__a;                           \
        })

static inline int errno_or_else(int fallback) {
        /* To be used when invoking library calls where errno handling is not defined clearly: we return
         * errno if it is set, and the specified error otherwise. The idea is that the caller initializes
         * errno to zero before doing an API call, and then uses this helper to retrieve a somewhat useful
         * error code */
        if (errno > 0)
                return -errno;

        return -ABS(fallback);
}

/* abs(3) says: Trying to take the absolute value of the most negative integer is not defined. */
#define _DEFINE_ABS_WRAPPER(name)                         \
        static inline bool ERRNO_IS_##name(intmax_t r) {  \
                if (r == INTMAX_MIN)                      \
                        return false;                     \
                return ERRNO_IS_NEG_##name(-ABS(r));      \
        }

/* For send()/recv() or read()/write(). */
static inline bool ERRNO_IS_NEG_TRANSIENT(intmax_t r) {
        return IN_SET(r,
                      -EAGAIN,
                      -EINTR);
}
_DEFINE_ABS_WRAPPER(TRANSIENT);

/* Hint #1: ENETUNREACH happens if we try to connect to "non-existing" special IP addresses, such as ::5.
 *
 * Hint #2: The kernel sends e.g., EHOSTUNREACH or ENONET to userspace in some ICMP error cases.  See the
 *          icmp_err_convert[] in net/ipv4/icmp.c in the kernel sources.
 *
 * Hint #3: When asynchronous connect() on TCP fails because the host never acknowledges a single packet,
 *          kernel tells us that with ETIMEDOUT, see tcp(7). */
static inline bool ERRNO_IS_NEG_DISCONNECT(intmax_t r) {
        return IN_SET(r,
                      -ECONNABORTED,
                      -ECONNREFUSED,
                      -ECONNRESET,
                      -EHOSTDOWN,
                      -EHOSTUNREACH,
                      -ENETDOWN,
                      -ENETRESET,
                      -ENETUNREACH,
                      -ENONET,
                      -ENOPROTOOPT,
                      -ENOTCONN,
                      -EPIPE,
                      -EPROTO,
                      -ESHUTDOWN,
                      -ETIMEDOUT);
}
_DEFINE_ABS_WRAPPER(DISCONNECT);

/* Transient errors we might get on accept() that we should ignore. As per error handling comment in
 * the accept(2) man page. */
static inline bool ERRNO_IS_NEG_ACCEPT_AGAIN(intmax_t r) {
        return ERRNO_IS_NEG_DISCONNECT(r) ||
                ERRNO_IS_NEG_TRANSIENT(r) ||
                r == -EOPNOTSUPP;
}
_DEFINE_ABS_WRAPPER(ACCEPT_AGAIN);

/* Resource exhaustion, could be our fault or general system trouble */
static inline bool ERRNO_IS_NEG_RESOURCE(intmax_t r) {
        return IN_SET(r,
                      -EMFILE,
                      -ENFILE,
                      -ENOMEM);
}
_DEFINE_ABS_WRAPPER(RESOURCE);

/* Seven different errors for "operation/system call/socket feature not supported" */
static inline bool ERRNO_IS_NEG_NOT_SUPPORTED(intmax_t r) {
        return IN_SET(r,
                      -EOPNOTSUPP,
                      -ENOTTY,
                      -ENOSYS,
                      -EAFNOSUPPORT,
                      -EPFNOSUPPORT,
                      -EPROTONOSUPPORT,
                      -ESOCKTNOSUPPORT,
                      -ENOPROTOOPT);
}
_DEFINE_ABS_WRAPPER(NOT_SUPPORTED);

/* ioctl() with unsupported command/arg might additionally return EINVAL */
static inline bool ERRNO_IS_NEG_IOCTL_NOT_SUPPORTED(intmax_t r) {
        return ERRNO_IS_NEG_NOT_SUPPORTED(r) || r == -EINVAL;
}
_DEFINE_ABS_WRAPPER(IOCTL_NOT_SUPPORTED);

/* Two different errors for access problems */
static inline bool ERRNO_IS_NEG_PRIVILEGE(intmax_t r) {
        return IN_SET(r,
                      -EACCES,
                      -EPERM);
}
_DEFINE_ABS_WRAPPER(PRIVILEGE);

/* Three different errors for "not enough disk space" */
static inline bool ERRNO_IS_NEG_DISK_SPACE(intmax_t r) {
        return IN_SET(r,
                      -ENOSPC,
                      -EDQUOT,
                      -EFBIG);
}
_DEFINE_ABS_WRAPPER(DISK_SPACE);

/* Three different errors for "this device does not quite exist" */
static inline bool ERRNO_IS_NEG_DEVICE_ABSENT(intmax_t r) {
        return IN_SET(r,
                      -ENODEV,
                      -ENXIO,
                      -ENOENT);
}
_DEFINE_ABS_WRAPPER(DEVICE_ABSENT);

/* Quite often we want to handle cases where the backing FS doesn't support extended attributes at all and
 * where it simply doesn't have the requested xattr the same way */
static inline bool ERRNO_IS_NEG_XATTR_ABSENT(intmax_t r) {
        return r == -ENODATA ||
                ERRNO_IS_NEG_NOT_SUPPORTED(r);
}
_DEFINE_ABS_WRAPPER(XATTR_ABSENT);

1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
2	#pragma once
3
4	#include <string.h>
5
6	#include "forward.h"
7
8	/* strerror(3) says that glibc uses a maximum length of 1024 bytes. */
9	#define ERRNO_BUF_LEN 1024
10
11	/* Note: the lifetime of the compound literal is the immediately surrounding block,
12	* see C11 §6.5.2.5, and
13	* https://stackoverflow.com/questions/34880638/compound-literal-lifetime-and-if-blocks
14	*
15	* Note that we use the GNU variant of strerror_r() here. */
16	#define STRERROR(errnum) strerror_r(ABS(errnum), (char[ERRNO_BUF_LEN]){}, ERRNO_BUF_LEN)
17
18	/* A helper to print an error message or message for functions that return 0 on EOF.
19	* Note that we can't use ({ … }) to define a temporary variable, so errnum is
20	* evaluated twice. */
21	#define STRERROR_OR_EOF(errnum) ((errnum) != 0 ? STRERROR(errnum) : "Unexpected EOF")
22
23	static inline void _reset_errno_(int *saved_errno) {	73,527,952✔
24	if (saved_errno < 0) / Invalidated by UNPROTECT_ERRNO? */	73,527,952✔
25	return;
26
27	errno = *saved_errno;	73,520,793✔
28	}
29
30	#define PROTECT_ERRNO \
31	_cleanup_(_reset_errno_) _unused_ int _saved_errno_ = errno
32
33	#define UNPROTECT_ERRNO \
34	do { \
35	errno = _saved_errno_; \
36	_saved_errno_ = -1; \
37	} while (false)
38
39	#define LOCAL_ERRNO(value) \
40	PROTECT_ERRNO; \
41	errno = ABS(value)
42
43	#define return_with_errno(r, err) \
44	do { \
45	errno = ABS(err); \
46	return r; \
47	} while (false)
48
49	static inline int negative_errno(void) {	2,771,697✔
50	/* This helper should be used to shut up gcc if you know 'errno' is
51	* negative. Instead of "return -errno;", use "return negative_errno();"
52	* It will suppress bogus gcc warnings in case it assumes 'errno' might
53	* be 0 and thus the caller's error-handling might not be triggered. */
54	assert_return(errno > 0, -EINVAL);	2,771,697✔
55	return -errno;	2,771,697✔
56	}
57
58	static inline int RET_NERRNO(int ret) {	39,206,069✔
59
60	/* Helper to wrap system calls in to make them return negative errno errors. This brings system call
61	* error handling in sync with how we usually handle errors in our own code, i.e. with immediate
62	* returning of negative errno. Usage is like this:
63	*
64	* …
65	* r = RET_NERRNO(unlink(t));
66	* …
67	*
68	* or
69	*
70	* …
71	* fd = RET_NERRNO(open("/etc/fstab", O_RDONLY\|O_CLOEXEC));
72	* …
73	*/
74
75	if (ret < 0)	39,206,069✔
76	return negative_errno();	2,771,647✔
77
78	return ret;
79	}
80
81	/* Collect possible errors in <acc>, so that the first error can be returned.
82	* Returns (possibly updated) <acc>. */
83	#define RET_GATHER(acc, err) \
84	({ \
85	int *__a = &(acc), __e = (err); \
86	if (*__a >= 0 && __e < 0) \
87	*__a = __e; \
88	*__a; \
89	})
90
91	static inline int errno_or_else(int fallback) {	71,720✔
92	/* To be used when invoking library calls where errno handling is not defined clearly: we return
93	* errno if it is set, and the specified error otherwise. The idea is that the caller initializes
94	* errno to zero before doing an API call, and then uses this helper to retrieve a somewhat useful
95	* error code */
96	if (errno > 0)	71,720✔
97	return -errno;	30✔
98
99	return -ABS(fallback);
100	}
101
102	/* abs(3) says: Trying to take the absolute value of the most negative integer is not defined. */
103	#define _DEFINE_ABS_WRAPPER(name) \
104	static inline bool ERRNO_IS_##name(intmax_t r) { \
105	if (r == INTMAX_MIN) \
106	return false; \
107	return ERRNO_IS_NEG_##name(-ABS(r)); \
108	}
109
110	/* For send()/recv() or read()/write(). */
111	static inline bool ERRNO_IS_NEG_TRANSIENT(intmax_t r) {	3,612,811✔
112	return IN_SET(r,	3,612,647✔
113	-EAGAIN,
114	-EINTR);
115	}
116	_DEFINE_ABS_WRAPPER(TRANSIENT);	5,922✔
117
118	/* Hint #1: ENETUNREACH happens if we try to connect to "non-existing" special IP addresses, such as ::5.
119	*
120	* Hint #2: The kernel sends e.g., EHOSTUNREACH or ENONET to userspace in some ICMP error cases. See the
121	* icmp_err_convert[] in net/ipv4/icmp.c in the kernel sources.
122	*
123	* Hint #3: When asynchronous connect() on TCP fails because the host never acknowledges a single packet,
124	* kernel tells us that with ETIMEDOUT, see tcp(7). */
125	static inline bool ERRNO_IS_NEG_DISCONNECT(intmax_t r) {	659,642✔
126	return IN_SET(r,	659,642✔
127	-ECONNABORTED,
128	-ECONNREFUSED,
129	-ECONNRESET,
130	-EHOSTDOWN,
131	-EHOSTUNREACH,
132	-ENETDOWN,
133	-ENETRESET,
134	-ENETUNREACH,
135	-ENONET,
136	-ENOPROTOOPT,
137	-ENOTCONN,
138	-EPIPE,
139	-EPROTO,
140	-ESHUTDOWN,
141	-ETIMEDOUT);
142	}
143	_DEFINE_ABS_WRAPPER(DISCONNECT);	2,674✔
144
145	/* Transient errors we might get on accept() that we should ignore. As per error handling comment in
146	* the accept(2) man page. */
147	static inline bool ERRNO_IS_NEG_ACCEPT_AGAIN(intmax_t r) {	×
148	return ERRNO_IS_NEG_DISCONNECT(r) \|\|	×
149	ERRNO_IS_NEG_TRANSIENT(r) \|\|	×
150	r == -EOPNOTSUPP;
151	}
152	_DEFINE_ABS_WRAPPER(ACCEPT_AGAIN);	×
153
154	/* Resource exhaustion, could be our fault or general system trouble */
155	static inline bool ERRNO_IS_NEG_RESOURCE(intmax_t r) {	1,299✔
156	return IN_SET(r,	1,299✔
157	-EMFILE,
158	-ENFILE,
159	-ENOMEM);
160	}
UNCOV 161	_DEFINE_ABS_WRAPPER(RESOURCE);	×
162
163	/* Seven different errors for "operation/system call/socket feature not supported" */
164	static inline bool ERRNO_IS_NEG_NOT_SUPPORTED(intmax_t r) {	302,414✔
165	return IN_SET(r,	98,378✔
166	-EOPNOTSUPP,
167	-ENOTTY,
168	-ENOSYS,
169	-EAFNOSUPPORT,
170	-EPFNOSUPPORT,
171	-EPROTONOSUPPORT,
172	-ESOCKTNOSUPPORT,
173	-ENOPROTOOPT);
174	}
175	_DEFINE_ABS_WRAPPER(NOT_SUPPORTED);	9,048✔
176
177	/* ioctl() with unsupported command/arg might additionally return EINVAL */
178	static inline bool ERRNO_IS_NEG_IOCTL_NOT_SUPPORTED(intmax_t r) {	200,132✔
179	return ERRNO_IS_NEG_NOT_SUPPORTED(r) \|\| r == -EINVAL;	200,132✔
180	}
181	_DEFINE_ABS_WRAPPER(IOCTL_NOT_SUPPORTED);	200,132✔
182
183	/* Two different errors for access problems */
184	static inline bool ERRNO_IS_NEG_PRIVILEGE(intmax_t r) {	700,843✔
185	return IN_SET(r,	697,038✔
186	-EACCES,
187	-EPERM);
188	}
189	_DEFINE_ABS_WRAPPER(PRIVILEGE);	3,873✔
190
191	/* Three different errors for "not enough disk space" */
192	static inline bool ERRNO_IS_NEG_DISK_SPACE(intmax_t r) {	×
193	return IN_SET(r,	×
194	-ENOSPC,
195	-EDQUOT,
196	-EFBIG);
197	}
198	_DEFINE_ABS_WRAPPER(DISK_SPACE);	×
199
200	/* Three different errors for "this device does not quite exist" */
201	static inline bool ERRNO_IS_NEG_DEVICE_ABSENT(intmax_t r) {	1,213,993✔
202	return IN_SET(r,	1,213,993✔
203	-ENODEV,
204	-ENXIO,
205	-ENOENT);
206	}
207	_DEFINE_ABS_WRAPPER(DEVICE_ABSENT);	136,615✔
208
209	/* Quite often we want to handle cases where the backing FS doesn't support extended attributes at all and
210	* where it simply doesn't have the requested xattr the same way */
211	static inline bool ERRNO_IS_NEG_XATTR_ABSENT(intmax_t r) {	42,219✔
212	return r == -ENODATA \|\|	42,219✔
213	ERRNO_IS_NEG_NOT_SUPPORTED(r);	42,219✔
214	}
215	_DEFINE_ABS_WRAPPER(XATTR_ABSENT);	32,232✔

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