Linux Interrupted System Call Error
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errno was set to EINTR. This was done under the assumption that since a signal occurred and the process caught it, there is a good chance that something has happened that should wake up interrupted system calls in unix the blocked system call. Here, we have to differentiate between a system call and interrupted system call python a function. It is a system call within the kernel that is interrupted when a signal is caught. To support this feature, interrupted system call zabbix the system calls are divided into two categories: the "slow" system calls and all the others. The slow system calls are those that can block forever. Included in this category are Reads that can block the
"interrupted System Call" Errno
caller forever if data isn't present with certain file types (pipes, terminal devices, and network devices)Writes that can block the caller forever if the data can't be accepted immediately by these same file typesOpens that block until some condition occurs on certain file types (such as an open of a terminal device that waits until an attached modem answers the phone)The pause function (which by definition puts the calling process to sleep until top: failed tty set: a signal is caught) and the wait functionCertain ioctl operationsSome of the interprocess communication functions (Chapter 15) The notable exception to these slow system calls is anything related to disk I/O. Although a read or a write of a disk file can block the caller temporarily (while the disk driver queues the request and then the request is executed), unless a hardware error occurs, the I/O operation always returns and unblocks the caller quickly. One condition that is handled by interrupted system calls, for example, is when a process initiates a read from a terminal device and the user at the terminal walks away from the terminal for an extended period. In this example, the process could be blocked for hours or days and would remain so unless the system was taken down. POSIX.1 semantics for interrupted reads and writes changed with the 2001 version of the standard. Earlier versions gave implementations a choice for how to deal with reads and writes that have processed partial amounts of data. If read has received and transferred data to an application's buffer, but has not yet received all that the application requested and is then interrupted, the operating system could either fail the system call with errno set to EINTR or allow the system call to succeed, retur
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Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; http://poincare.matf.bg.ac.rs/~ivana/courses/tos/sistemi_knjige/pomocno/apue/APUE/0201433079/ch10lev1sec5.html it only takes a minute: Sign up How to handle EINTR (interrupted System Call) up vote 3 down vote favorite 3 My user-space application sometimes blocks after receiving an EINTR-Signal, somehow. What I recorded with strace: time(NULL) = 1257343042 time(NULL) = 1257343042 rt_sigreturn(0xbff07be4) = -1 EINTR (Interrupted system call) --- SIGALRM (Alarm clock) @ 0 (0) --- time(NULL) = 1257343042 http://stackoverflow.com/questions/1674162/how-to-handle-eintr-interrupted-system-call futex(0xb7cea80c, 0x80 /* FUTEX_??? */, 2) = ? ERESTARTSYS (To be restarted) --- SIGUSR1 (User defined signal 1) @ 0 (0) --- sigreturn() = ? (mask now [ALRM]) futex(0xb7cea80c, 0x80 /* FUTEX_??? */, 2) = ? ERESTARTSYS (To be restarted) --- SIGWINCH (Window changed) @ 0 (0) --- futex(0xb7cea80c, 0x80 /* FUTEX_??? */, 2) = ? ERESTARTSYS (To be restarted) --- SIGTERM (Terminated) @ 0 (0) --- time(NULL) = 1257343443 time(NULL) = 1257343443 futex(0xb7cea80c, 0x80 /* FUTEX_??? */, 2) = ? ERESTARTSYS (To be restarted) --- SIGWINCH (Window changed) @ 0 (0) --- futex(0xb7cea80c, 0x80 /* FUTEX_??? */, 2 Can I catch the EINTR signal and how can I repeat concerned calls such as write, read or select? How can I determine WHERE this EINTR occurred, even if I used third-party libraries working with system calls? Why my app is completely blocked after receiving an EINTR (see strace dump: I sent a SIGUSR1 which normally should be handled)? And why is futex() returning ERESTARTSYS to user space? thanks c++ c linux share|improve this question asked Nov 4
errno was set to EINTR. This was done under the assumption that since a signal occurred and the process caught it, there is a good chance that something has happened that should wake up the blocked http://poincare.matf.bg.ac.rs/~ivana/courses/tos/sistemi_knjige/pomocno/apue/APUE/0201433079/ch10lev1sec5.html system call. Here, we have to differentiate between a system call and a function. It is a system call within the kernel that is interrupted when a signal is caught. To support this feature, the system calls are divided into two categories: the "slow" system calls and all the others. The slow system calls are those that can block forever. Included in this category are Reads that can block the caller forever if data isn't present interrupted system with certain file types (pipes, terminal devices, and network devices)Writes that can block the caller forever if the data can't be accepted immediately by these same file typesOpens that block until some condition occurs on certain file types (such as an open of a terminal device that waits until an attached modem answers the phone)The pause function (which by definition puts the calling process to sleep until a signal is caught) and the wait functionCertain interrupted system call ioctl operationsSome of the interprocess communication functions (Chapter 15) The notable exception to these slow system calls is anything related to disk I/O. Although a read or a write of a disk file can block the caller temporarily (while the disk driver queues the request and then the request is executed), unless a hardware error occurs, the I/O operation always returns and unblocks the caller quickly. One condition that is handled by interrupted system calls, for example, is when a process initiates a read from a terminal device and the user at the terminal walks away from the terminal for an extended period. In this example, the process could be blocked for hours or days and would remain so unless the system was taken down. POSIX.1 semantics for interrupted reads and writes changed with the 2001 version of the standard. Earlier versions gave implementations a choice for how to deal with reads and writes that have processed partial amounts of data. If read has received and transferred data to an application's buffer, but has not yet received all that the application requested and is then interrupted, the operating system could either fail the system call with errno set to EINTR or allow the system call to succeed, returning the partial amount of data received. Similarly, if write is interrupted after transferring some of the dat