第11章可调内核参数

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1 11 11 Unix BSD 4.4 Linux sysctl Unix Linux /proc window /proc /proc/sys /proc/sys sysctl Unix root /proc/sys/vm root /proc/sys sysctl /proc/sys struct ctl_table struct ctl_tables /proc/sys struct ctl_table_entry root_table30328 struct ctl_table child child ctl_table struct ctl_table typedef root_table struct ctl_table ctl_name

2 ctl_table struct ctl_table ctl_name procname/proc/sys data int char maxlen data data int maxlen sizeofint mode Unix /proc Unix Linux

3 11 ls -l rw x 11.2 mode 9 mode setuid setgid r w x r w x r w x other process user group other 11.2 mode mode mode r w x test_perm maxlen 0mode child child table data NULL maxlen 0 proc_handlerdata /proc data proc_handler Proc_handler proc_dostring proc_dointvec prototype proc_ handler NULL strategy data sysctl sysctl_string31121 stringctl_intvec31163 /proc sysctl NULL de struct proc_dir_entry /proc struct ctl_table /proc extra extra

4 11 /proc/sys /proc/sys /proc /proc kernel/sysctl.c /proc /proc register_proc_table 30689register_proc_table /proc/sys ctl_table ctl_table root /proc/sys root proc_sys_root table clt_name ctl_table procname NULL /proc/sys procname/proc/sys proc _handler child 30711proc_handler child ctl_table proc_handler child de de NULL table create_proc_entry register_proc_table proc_sys_ inode_operations30295 proc_sys_inode_operations proc_readsys proc_writesys de NULL register_proc_table unregister_proc_table 30739unregister_proc_table ctl_table /proc ctl_ table /proc/sys

5 /proc/sys NULL de 30748/proc unregister_proc_table unregister_proc_table proc_unregister do_rw_proc 30771do_rw_proc proc_readsys30802 proc_writesys30806 /proc ctl_table 30782/proc/sys table de->data proc_handler proc_ handler proc_handler proc_dostring proc_ dointvec do_rw_proc res count proc_dostring proc_dostring C write write stub /proc ASCII NUL0 lenp NULL C NUL L ASCII lenp buffer

6 11 table->maxlen NUL struct file f_pos tell seek proc_doutsstring uts_sem proc_doutsstring proc_dostring kern_table30341 system_utsname do_proc_dointvec 30881proc_dointvec30972 do_proc_dointvec table data int int lenp 1 int int buffer int int ASCII /proc int left int vleft table->data if P556 1 write buf NUL bufbuf ASCII buf 20TMPBUFLEN30885 buf 64 ASCII NUL ,223,372,032,854,775, buffer

7 11 simple_strtoul conv proc_dointvec _jiffies HZ jiffies argument-separating argument buf i ASCII tab tab conv buf tab buf sprintf buf buf tab p buf buf p p buf reason gcc int if ASCII NUL lenp lenp

8 11 proc_dointvec_minmax 30978proc_dointvec_minmax do_proc_dointvec extra1 extra2 extra1 extra2 proc_dointvec_minmax conv min max extra1 extra2 min max val min max buffer val min max val min min max min max buffer P558 1 Linux sysctl sysctl sysctl /proc sysctl C /proc shell C sysctl / sysctl do_sysctl 30471do_sysctl sys_sysctl30504 sysctl sys_sysctl sysctl stub oldval oldval newval newval oldlenp newlen oldval newval NULL NULL oldval

9 oldlenp old_len register_sysctl_table 30493parse_table30560 / 30495parse_table 30497ENOTDIR error DLIST_NEXT loop iterator 30501ENOTDIR parse_table 30560parse_table int name ctl_table int / name for for ( ; nlen ; ++name, --nlen, table = table -> child ) name table->ctl_ name name n ctl_name name ctl_table wildcard CTL_ANY17761 CTL_ANY CTL_ANY 2.0 sysctl Unix x /proc 30579strategy

10 name nlen 1 do_sysctl_strategy30603 / 30598name parse_table ENOTDIR do_sysctl_strategy 30603do_sysctl_strategy ctl_table / strategy / strategy / 30610oldval r op newval w EPERM strategy / 0 0strategy 0 strategy get_user maxlen 30634oldval oldlenp oldlenp maxlen copy_from_user tabel->data / maxlen 0 sysctl 8 sys_brk33155 brk maxlen 0 0 maxlen maxlen

11 11 sysctl man do_sysctl_strategy EPERM register_sysctl_table ctl_table 30655struct ctl_table_header 30659ctl_tables register_proc_table30689 /proc/sys /proc unregister_sysctl_table30672 unregister_sysctl_table ctl_table /proc /proc root_table_header30256 root_table unregister_sysctl_table root_table_header sysctl_string 31121sysctl_string ctl_table do_sysctl_strategy / ENOTDIR do_sysctl_strategy NUL lenp NUL if ( copy_to_user ( oldval, table -> data, len + 1 ) ) return EFAULT ; table->data table->maxlen char table->data > >= table->data NUL NUL table->maxlen table->maxlen len table->maxlen NUL table->data[len+1]

12 NUL NUL data NUL NUL table->data newval NUL sysctl_string sysctl_intvec 31163sysctl_intvec kernel/sysctl.c int sysctl_intvec int do_sysctl_strategy30603 sysctl_intvec get_user sysctl_intvec 0 do_sysctl_strategy get_user garbage value EINVAL EFAULT bug sysctl_intvec proc_dointvec_minmax ctl_table handler routineproc_dointvec_minmax sysctl_intvec ctl_tables proc_dointvec_minmax proc_dointvec_minmax ctl_table proc_dointvec_ minmax sysctl_intvec table->data do_sysctl_strategy table->data

C/C++ - 文件IO

C/C++ - 文件IO C/C++ IO Table of contents 1. 2. 3. 4. 1 C ASCII ASCII ASCII 2 10000 00100111 00010000 31H, 30H, 30H, 30H, 30H 1, 0, 0, 0, 0 ASCII 3 4 5 UNIX ANSI C 5 FILE FILE 6 stdio.h typedef struct { int level ;

第11章 可调内核参数

第11章可调内核参数