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* Allow certain operations to succeed even if we don't have write

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permission to the Nix store or database.  E.g., `nix-env -qa' will
  work, but `nix-env -qas' won't (the latter needs DB access).  The
  option `--readonly-mode' forces this mode; otherwise, it's only
  activated when the database cannot be opened.
This commit is contained in:
Eelco Dolstra 2004-10-25 14:38:23 +00:00
parent 3ade3e7721
commit f4d44a0026
9 changed files with 58 additions and 16 deletions
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24
src/libstore/store.cc
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@ -21,7 +21,7 @@ static Database nixDB;
The existence of a key $p$ indicates that path $p$ is valid (that
is, produced by a succesful build). */
static TableId dbValidPaths;
static TableId dbValidPaths = 0;
/* dbSuccessors :: Path -> Path
@ -32,14 +32,14 @@ static TableId dbValidPaths;
Note that a term $y$ is a successor of $x$ iff there exists a
sequence of rewrite steps that rewrites $x$ into $y$.
*/
static TableId dbSuccessors;
static TableId dbSuccessors = 0;
/* dbSuccessorsRev :: Path -> [Path]
The reverse mapping of dbSuccessors (i.e., it stores the
predecessors of a Nix expression).
*/
static TableId dbSuccessorsRev;
static TableId dbSuccessorsRev = 0;
/* dbSubstitutes :: Path -> [(Path, Path, [string])]
@ -54,14 +54,14 @@ static TableId dbSuccessorsRev;
substitute for that derivate. The substitute in this case might be
a Nix expression that fetches the Nix archive.
*/
static TableId dbSubstitutes;
static TableId dbSubstitutes = 0;
/* dbSubstitutesRev :: Path -> [Path]
The reverse mapping of dbSubstitutes; it maps store expressions
back to the paths for which they are substitutes.
*/
static TableId dbSubstitutesRev;
static TableId dbSubstitutesRev = 0;
bool Substitute::operator == (const Substitute & sub)
@ -74,7 +74,14 @@ bool Substitute::operator == (const Substitute & sub)
void openDB()
{
nixDB.open(nixDBPath);
if (readOnlyMode) return;
try {
nixDB.open(nixDBPath);
} catch (DbNoPermission & e) {
printMsg(lvlTalkative, "cannot access Nix database; continuing anyway");
readOnlyMode = true;
return;
}
dbValidPaths = nixDB.openTable("validpaths");
dbSuccessors = nixDB.openTable("successors");
dbSuccessorsRev = nixDB.openTable("successors-rev");
@ -433,7 +440,7 @@ Path addToStore(const Path & _srcPath)
string baseName = baseNameOf(srcPath);
Path dstPath = canonPath(nixStore + "/" + (string) h + "-" + baseName);
if (!isValidPath(dstPath)) {
if (!readOnlyMode && !isValidPath(dstPath)) {
/* The first check above is an optimisation to prevent
unnecessary lock acquisition. */
@ -445,6 +452,9 @@ Path addToStore(const Path & _srcPath)
if (!isValidPath(dstPath)) {
if (pathExists(dstPath)) deletePath(dstPath);
/* !!! race: srcPath might change between hashPath() and
here! */
copyPath(srcPath, dstPath);