diff options
author | Ian Jackson <ian.jackson@eu.citrix.com> | 2012-06-28 18:43:22 +0100 |
---|---|---|
committer | Ian Jackson <ian.jackson@eu.citrix.com> | 2012-06-28 18:43:22 +0100 |
commit | 68c6062f0cbfd61dbf8839a1b721ea3c00072f26 (patch) | |
tree | 46af85ef196ca49bec57dab3122da7f36c9eacee /tools | |
parent | a8b4c682ca0153f32c2d17e6973dd2e9e2cae162 (diff) | |
download | xen-68c6062f0cbfd61dbf8839a1b721ea3c00072f26.tar.gz xen-68c6062f0cbfd61dbf8839a1b721ea3c00072f26.tar.bz2 xen-68c6062f0cbfd61dbf8839a1b721ea3c00072f26.zip |
libxl: provide libxl__xs_*_checked and libxl__xs_transaction_*
These useful utility functions make dealing with xenstore a little
less painful.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Diffstat (limited to 'tools')
-rw-r--r-- | tools/libxl/libxl_internal.h | 38 | ||||
-rw-r--r-- | tools/libxl/libxl_xshelp.c | 76 |
2 files changed, 114 insertions, 0 deletions
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index 890490482a..87ca72109d 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -498,6 +498,44 @@ _hidden bool libxl__xs_mkdir(libxl__gc *gc, xs_transaction_t t, _hidden char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid); + +/*----- "checked" xenstore access functions -----*/ +/* Each of these functions will check that it succeeded; if it + * fails it logs and returns ERROR_FAIL. + */ + +/* On success, *result_out came from the gc. + * On error, *result_out is undefined. + * ENOENT counts as success but sets *result_out=0 + */ +int libxl__xs_read_checked(libxl__gc *gc, xs_transaction_t t, + const char *path, const char **result_out); + +/* Does not include a trailing null. + * May usefully be combined with GCSPRINTF if the format string + * behaviour of libxl__xs_write is desirable. */ +int libxl__xs_write_checked(libxl__gc *gc, xs_transaction_t t, + const char *path, const char *string); + +/* ENOENT is not an error (even if the parent directories don't exist) */ +int libxl__xs_rm_checked(libxl__gc *gc, xs_transaction_t t, const char *path); + +/* Transaction functions, best used together. + * The caller should initialise *t to 0 (XBT_NULL) before calling start. + * Each function leaves *t!=0 iff the transaction needs cleaning up. + * + * libxl__xs_transaction_commit returns: + * <0 failure - a libxl error code + * +1 commit conflict; transaction has been destroyed and caller + * must go round again (call _start again and retry) + * 0 committed successfully + */ +int libxl__xs_transaction_start(libxl__gc *gc, xs_transaction_t *t); +int libxl__xs_transaction_commit(libxl__gc *gc, xs_transaction_t *t); +void libxl__xs_transaction_abort(libxl__gc *gc, xs_transaction_t *t); + + + /* * This is a recursive delete, from top to bottom. What this function does * is remove empty folders that contained the deleted entry. diff --git a/tools/libxl/libxl_xshelp.c b/tools/libxl/libxl_xshelp.c index c5b5364c56..993f527c58 100644 --- a/tools/libxl/libxl_xshelp.c +++ b/tools/libxl/libxl_xshelp.c @@ -135,6 +135,82 @@ char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid) return s; } +int libxl__xs_read_checked(libxl__gc *gc, xs_transaction_t t, + const char *path, const char **result_out) +{ + char *result = libxl__xs_read(gc, t, path); + if (!result) { + if (errno != ENOENT) { + LOGE(ERROR, "xenstore read failed: `%s'", path); + return ERROR_FAIL; + } + } + *result_out = result; + return 0; +} + +int libxl__xs_write_checked(libxl__gc *gc, xs_transaction_t t, + const char *path, const char *string) +{ + size_t length = strlen(string); + if (!xs_write(CTX->xsh, t, path, string, length)) { + LOGE(ERROR, "xenstore write failed: `%s' = `%s'", path, string); + return ERROR_FAIL; + } + return 0; +} + +int libxl__xs_rm_checked(libxl__gc *gc, xs_transaction_t t, const char *path) +{ + if (!xs_rm(CTX->xsh, t, path)) { + if (errno == ENOENT) + return 0; + + LOGE(ERROR, "xenstore rm failed: `%s'", path); + return ERROR_FAIL; + } + return 0; +} + +int libxl__xs_transaction_start(libxl__gc *gc, xs_transaction_t *t) +{ + assert(!*t); + *t = xs_transaction_start(CTX->xsh); + if (!*t) { + LOGE(ERROR, "could not create xenstore transaction"); + return ERROR_FAIL; + } + return 0; +} + +int libxl__xs_transaction_commit(libxl__gc *gc, xs_transaction_t *t) +{ + assert(*t); + + if (!xs_transaction_end(CTX->xsh, *t, 0)) { + if (errno == EAGAIN) + return +1; + + *t = 0; + LOGE(ERROR, "could not commit xenstore transaction"); + return ERROR_FAIL; + } + + *t = 0; + return 0; +} + +void libxl__xs_transaction_abort(libxl__gc *gc, xs_transaction_t *t) +{ + if (!*t) + return; + + if (!xs_transaction_end(CTX->xsh, *t, 1)) + LOGE(ERROR, "could not abort xenstore transaction"); + + *t = 0; +} + int libxl__xs_path_cleanup(libxl__gc *gc, xs_transaction_t t, char *user_path) { unsigned int nb = 0; |